That's false.
The Wii sold 25.95 million units during its 3rd year 20.53 million in its 4th year on the market, 15.08 million in year 5. All years above the peak performance of the competition (14.3M by PS3 in fy2011), and only in the 6th year did it fall below: but at 9.84 million it was still strongly competing with the now matured ugly duckling PS3 console, and it was only in 2013 (year 7) that the Wii fell significantly below PS3 in sales (3.98m vs 8.4m) Hardly the drop from being a top brand in 2 years flat you claimed. It should also be noted that PS3 sales fizzled in year 8 (2014); not a significantly longer period of success.
https://www.statista.com/statistics/227012/lifetime-unit-sales-of-nintendos-home-consoles/
https://www.statista.com/statistics/651584/global-ps3-console-unit-sales/

The SNES peaked in its second year (with the exception of Japan) http://gamrconnect.vgchartz.com/reply.php?id=240588&quote=9035461

The only reason the NES "finished strong" is because of its staggered launch: while launching in 1983, it was still launching in certain cities for the first time as late as 1993 in Europe (1991 in the West). It would be dishonest to say the NES had a "strong finish" when in many places it didn't even start the race until the very end.

Dropping by 5 million a year every year for three years is a fairly negative trend even if the peak was quite high, that indicated Wii peaked and then started a downward trajectory which eventually led to the brand completely falling apart and having dropped off dramatically by 2011. 

NES had a staggered launch sure, but Nintendo wasn't like forced to release a new game every month for it towards the end, in 1989 and 1990 they basically just held Super Mario 3 off and it didn't really make any difference because they could afford to not have to carry the platform so much on their own shoulders in those days. 

"Championing MS and Sony" lol, ok, jeezus can you any more corporate obsessed? These aren't religions or even sports teams. Who cares, I'm merely citing that mid-gen Pro style refreshes do provide mid-cycle sales boosts. Argue that if you want but you probably really can't. 

I would expect sales of Switch to be solid through 2020 as I expect BOTW2 + new 3D Mario to go with AC and Bayo 3, but "2021 is a given no matter what" yeah ... no, not sure if I'm buying that kool-aid. 

By 2021, they'll likely have used up every major IP they have and even doubled down on IPs like 3D Zelda and 3D Mario. 

I think that's where they will start to see some decline, 2020 is still in the 3 year range. 2021, 2022 are more problematic I think. 

Just sequel-izing IP that are already on the Switch and selling to a big chunk of the userbase isn't going to be the be-all answer, with BOTW2 for example a large portion of the people who would be buying it are going to naturally be some of the 12 million+ that are Zelda fans that already have the Switch for BOTW1. So each successive sequel your "hardware sales bump" diminishes. 

Quality isn't the only issue, BOTW is tremendous quality, that actually works against BOTW2 being as large of a system seller because BOTW is so good that it brings in so many people to begin with that the sequel doesn't have anywhere near as large of a net to cast to get new hardware buyers from. 

New IP can certainly do the trick but it's also like buying a lottery ticket, there's no guarantee whatsoever that your new IP is going to be a big hardware driving hit. 

Did the New 3DS or 2DS cause a lasting boost in 3DS sales? Or even a YoY boost that was significant? No? Then it wasn't as effective from an actual statistical perspective. 

Yes Switch can have more Mario and Zelda etc. games on it because of unified development setup, I never claimed that to not be the case, the issue is by 2021, who really are you bringing in that's new when you already have 2-3 major representations of said IP on the system already?

The fact is by the end of 2020 they'll have used up basically all their major IP and even doubled up likely on several of them. You can sequelize more from there but you end up hitting a saturation point because the previous games sell so well that they already have brought in most of the audience that would buy a system for that IP so now you're kinda just selling to same people who already own the system. 

I don't think 2021 + 2022 being defacto smooth sailing is some unassailable opinion that can't be challenged. We will see how that goes for Nintendo if they decide to really not rely at all on any kind of serious hardware refresh. My guess is they will start to see fairly notable declines in hardware sales at that point if they do that. 

Which will be interesting to see how they react since in the past they always had two hardware lines to kind of mitigate the impact from the down cycle period of hardware generations. 

Price cuts haven't really ever stopped declining/aging Nintendo hardware sales past a short term boost.

I don't think they have much interest in giving up the $300 price bracket either, they like the lucrative profit margins they get at that price point. The Lite model is basically a way for them to keep the base Switch at $300 for a long time, because if you're cheap/broke/8-years-old well then the Lite option is made for you. 

2021 and 2022 will be a challenge for them IMO but we'll see. 

Switch is doing better than 3DS but it's not like it's light years ahead either, the Switch is at 32.3 million as of end of January 2019, 3DS was at about 30 million at the same equivalent time point in its product cycle. The 3DS did actually have reasonably decent sales in its first 3 years or so outside of one poor 4-5 month stretch post launch, but it really hit a brick wall after about (again) for the fiscal year of 2014-2015 (March). 

4 years at the earliest??

The history of them spending 7 years one one handheld no longer makes sense, the biggest reason for that was software support and vastly different hardware with unique USPs. Nintendo has hit gold with the Switch, the Switch 2 will most likely just be a better version of the 1st, so why wait til 2023? Its not like they sell hardware at loss, they dont have to wait to recoup their losses before they start bleeding again. The truth in the past they would of had to decide which platform to support or rebuild games from the ground up for different very didfferent hardware. In the modern age thats obviously not happening and they could easily support a Switch and Switch 2 simultaneously, whilst rejuvenating interest in the brand and software support.

I  think some of you forget how quickly Nintendo consoles fall in sales in their late life as well as forgetting the revenue potential of having 3rd party games sell on your platform. Its not about chasing PS5 and X4, its about offering the relevant hardware when your audience demands it and for the first time in decades actually being viable as most a primary platform for most gamers.

The timing of the Switch 2 should be a calculated meassurement of demand in the market, new financial opportunities and an affordable technological leap to enable those opportunities. I dont know when that will be but I think Ninty is just a few months from burning through all their best sellers with hardware which is already presenting limitations and shortfalls both for consumers and for developers. We shouldnt assume Nintendo will wait until the Switch stops selling or set a rigid length of time for which it considers a generation.

I agree about Switch Pro being unless though. Ultimately if they offer a more power system it shouldnt just be to fix a games framerate or hit 1080p, but to offer a whole new promising future of new nintendo and third party games.

I would expect it to sell past the 3DS, just pointing out that to date the Switch isn't *that* far ahead of the 3DS. $250 was always a ridiculous price point for what the 3DS was offering anyway, Nintendo thought they could get away with it because of the 3D screen gimmick, it was always a $199.99 proposition and even that was probably pushing it but they were arrogant in that era and thought any kind of gimmick they threw out there + 3D puppies would be a smash hit. They were wrong. 

I think this fiscal year will be the peak sales year for the Switch, then the following year (primarily 2020) will see about even sales, it's 2021 and 2022 that I think are going to see notable declines.

The 2020 lineup lets say is: Animal Crossing, Zelda: BOTW2, Mario 3D 2 (EAD Tokyo), and Bayonetta 3 amongst other lesser games. 

2021 lineup then is what? Pokemon 3rd title, ok, but at this point you've already released two major Pokemon titles on the system, the 3rd pass at it likely doesn't yield big returns in terms of hardware boost. Metroid? OK, not really ever a big seller. More Mario or Zelda? You're kinda hitting up against diminishing returns there as there's so much Mario/Zelda content on the system by this time. 

2022 is even more problematic. 

The core problem I think is that you need really about 15-16 system selling IP to carry a platform through a really successful 5-6 year cycle and Nintendo has about 8 (2D Mario, 3D Mario, Mario Kart, Zelda, Pokemon, Smash Bros., Splatoon, Animal Crossing) and by about year 4 you've really already used all of these once and in some cases more than once. 8 is nothing to scoff at for a regular publisher, but Nintendo has much more burden on their shoulders than a regular publisher. You have B-tier sellers below that like Kirby, Yoshi, Fire Emblem, but they're not really selling mass amounts of hardware. 

That's where I think for Nintendo's case, a strict 1980s style 5-6 year product cycle doesn't really make sense. 

I think probably what would make more sense is a phased type of transition that is more gradual and not so sudden, ie: "Switch 2" launches in March/April 2021 (4 years in), but there are still many, maybe even a majority of Nintendo published titles that work on both the OG Switch and the new generation Switch. 

Or the mid-gen major refresh approach. Both would help mitigate the problem of the console down cycle that hits Nintendo particularly hard and it's something that is a bigger problem when you only have one hardware line to carry the company with. 

That doesn't help your "Wii fizzled out after two years flat" argument in the slightest, since you are now saying it fell apart in 2011, which is the fifth year, not the second or third year.

Looking at your other claims:
* 5 million drop is highly negative.
* 2011 is when the Wii collapsed when it sold 15.09 million (still higher than the peak of the competition, I might add).
* That the SNES had a strong lifecycle.

Let's look at the sales data:

* In year 4 the Wii had dropped by 5.42 million to 20.53 million from its year 3 peak of 25.95 million, a decline of 21%.
* In year 5 the Wii fell an additional 5.44 million to 15.09 million, bringing that decline to 43% from peak year 3 levels.
* In Fiscal Year 3 aligned, the SNES sold 12.03 million units, but this fell by 7.09 million to 4.94 million units during year 4, that amounts to a 59% drop.
* It wasn't until year 6, at 62% decline from the year 3 peak that the Wii had a statistical tie of decline during the SNES's 4th year alone.

Now let's draw some conclusions:

Your assertions regarding the Wii are inconsistent with your assertions regarding the SNES.

* If a 5 million drop marks a turn to failure, then surely the SNES's 7.09 million drop during its 3rd to 4th year marks it as a failure as well.
* If the Wii's decline by 43% in its 5th year from its 3rd year marks a failure, then certainly the 59% from the SNES's 3rd to 4th years marks a far greater failure.

From all of this we can deduce one of two possibilities: if the Wii failed in its 5th year then the SNES certainly failed in its 4th year, OR, if the SNES didn't fail in its 4th year, then the Wii didn't fail until its 7th year or later.

The "at the earliest" bit was probably unnecessary, as 2024 or later would be a bit too long IMO, but I stand by it not needing a successor before 2023.

Switch is in a better position for long term momentum than almost all prior Nintendo systems as it won't have the problem of their first party support being spread thin across multiple concurrent platforms (like how the 3DS and Wii U drained Wii's software support from 2011) and it has a monopoly over its niche in the market and indeed over the portable space now that Sony has raised the white flag over the Vita's grave.

As far as third party goes, yeah, it's not gonna be sharing AAA blockbusters with PS5 and Scarlet, but it doesn't need to; it's still going to get the kind of AA Japanese titles the 3DS had, plus indies and exclusive deals like Astral Chain, Marvel Ultimate Alliance 3, Daemon x Machina, Bayonetta, Shin Megami Tensei V, etc. 

The 3DS got 6 years, and the Switch is on track to outpace the 3DS considerably, why cut a wildly successful platform short of its full potential?

I am disappointed that the Lite and this are likely going to be used to put a floor under the Switch's price, but I have to say this is a really fair way to do upgrades.

A portable only affordable option for those who want it, and incremental improvements to the mainstream model that don't increase the price, make existing owners feel like they have been screwed or have any other major drawbacks.