If you are saying that the Switch will be supported for a long-time, I certainly agree. It won't be dropped like the N64, GCN, Wii (drop relative to how successful it was, it wasn't dropped as quickly as the others I'm mentioning) and Wii U. Even the 3DS which couldn't quite manage half of the DS sales still is available in some stores and has not been officially discontinued yet after 9 years. Though that day is coming any moment now since all models but the 2DS and 2DS XL were discontinued last year and first-party support ended.
But if you're implying that we will probably wait until 2025 or 2026 for the Switch's successor, I very much disagree. I know Nintendo gave up on hardware parity long ago. And the Switch is a hybrid that does not directly compete with Xbox and PlayStation, but it is still a competitor. Even a Switch Pro upgrade between 2021-2023 wouldn't be enough to keep up consumer interest all the way until 2025-2026. A new platform creates interest, and to compete in entertainment Nintendo needs to strike while the iron is hot. I think the Switch's successor will probably come out in 2023, maybe 2024 at the latest.

The other thing with revisions from this point on is really what is going to be the appeal.

The Switch had two discernible aspects that needed to be revised ... a smaller/cheaper model and better battery life, and Nintendo basically addressed both issues with the Lite revision and the Mariko revision which has far better battery life.

You could increase the screen size I guess, but the standard Switch already has a fairly large display, so that's not something that's really going to blow people away.

A Pro-like upgrade where you seriously upgrade the specs comes with the issue of games potentially not being able to run on older units. And I have to think if that was coming out it would've been planned for this year.

I think they'll do a model that has a larger screen and some cosmetic differences, but that's not really going to significantly alter sales trajectory. Battery life or the need for a smaller/cheaper model are no longer things people are really clamouring for as the two Switch revisions already basically address that.

I think Nintendo will follow the same overall trend that the industry is moving towards.... backward compatible hardware upgrades. Similar to MS and Sony, I believe the next Switch will be kind of like a Pro or X version, with around PS4 level performance. For a handheld that would be insane. In the past, system architectures changed a lot between generations... with Sony and MS opting for x86 and Nintendo with the Arm Based Tegra, allows for future iterations of hardware to be more scalable. I think that is why Nintendo chose the Tegra. A PS4 level Switch could most likely play a lot of next gen games, albeit at lower resolutions and framerates. The same situation as now. Also, Nintedo's own games don't usually require a lot of hardware power compared to the competition, but I assume it would be like the RAM expansion on the N64. Newer games would be playable on the older hardware but with maybe less settings and features... similar to Perfect Dark on the N64 and it's requirement for the RAM expansion for multiplayer (if my memory serves correct). I could see a mid generation spike in sales of the current Switch with a price drop in anticipation of an upcoming revision.

You could do more of a phased transition like

2023 lineup like this

Switch 2 - $349.99
Switch (standard) - $229.99
Switch Lite - $169.99

Switch 2 exclusive titles -
Mario Kart 9
Splatoon 3
Metroid Prime 4
Xenoblade Next
New Platinum Games Title
Third party titles like Final Fantasy VII Remake, The Witcher 4, Resident Evil 4 Remake, Call of Duty, new engine FIFA.


Switch + Switch 2 cross platform titles

New 2D Super Mario Bros.
Ring Fit 2
Pikmin 4
New Pokemon game
New Fire Emblem game
Legend of Zelda: Wind Waker HD
Octopath Traveller 2
Indie games

Cross gen games on Switch 2 run enhanced at 1080p portable + 4K docked. Pokemon just jumped to this new 3D engine so they'll probably milk that for a while.

I think that's a reasonably doable, that said Nintendo likely will want people not to linger on Switch 1 too long.

That's a hypothetical best case lineup, the reality likely wouldn't be that robust, more of an example of games that could be cross gen. And it's not like that Switch 2 money is going to charity. It would make Nintendo a lot of money both ways, a lot more than just having a Switch 1. 

Yeah DSi and New 3DS type upgrades don't really cause a long term boost. They are boring types of upgrades to (by then) very old hardware. 

GBC was a different type of situation designed more to cash in on the Pokemon craze of the time and buy them time so that GBA could be made because they screwed up with Project: Atlantis and basically had to start from scratch with the less ambitious GBA. But obviously the jump from no-color to actual NES+ tier color was a huge one. 

I don't really know how much you can do to the current Switch revisions. The Lite addresses the need for a smaller, portable centric Switch, Switch Mariko boosts battery life back to levels that 3DS/2DS had. Like I said probably they can do models with a larger screen but the current Switch already has a pretty good sized screen, don't think such a feature is setting the world on fire.

A Pro model opens up a can of worms of splintering the userbase and if its not out until 2021 anyway, I think Nintendo is just better off passing on that proposition and focusing on an actual successor for 2023. 

I think you're more or less right. 

I think the next thing coming is a Console only version. A pretty small little box with a unique colored Pro controller. It will have 100gb or more for storage, still takes cartridges. Probably faster than the other Switches, like how the New 3DS was a little faster at loading. $299.99.

They can create a special dock that takes over all processing duties, but the Switch unit itself would be doing nothing, so it would be more like a "Switch Pro" that you can recharge your current Switch handheld on.
The USB-C port on the Switch means that the dock can never "augment" the processing capabilities of the handheld, it's bandwidth is insufficient and it's latency is far to high. (Not to mention a few other technical barriers which I won't get into here with how data transmissions are managed.)

just my take on that particular question.  I do buy a nintendo platform specifically for zelda metroid prime and luigis mansion, but if those were the only games available id sell my system afterwards or id simply pass on buying it.  3rd party variety is the core gamers bread and butter. To omit them would be omitting that demographic.  Id argue the last time 10do did that, we got the wii, which was wildly succeasful amomg casuals, but had a fairly poor attach rate among more core oriented titles. The backlash manifested as the wii-u. Core gamers had brushed off the wii as a 1 trick pony gimmick system and were not about to pay mind to 10dos "unprecedented 3rd party support" and rightfully so in the end. Late, underwhelming or non existent ports  became par for the course w the u and what was the backbone of the wiiu e3 demonstration? Nindendo land. Another gimmicky casual game. So, in my opinion, 3rd parties are still pretty darn important to fill out a consoles library. Unless 10dos willing to up their game and start producing a large amount of the AAA commercially successful core games their 1st party catalogs lack (which id say theyve shown almost no interest in doing), id say 3rd parties are atill pretty important.  Yeah I could b wrong. Just my take on thr subject.

2021 is probably too late for a Pro model that fragments the userbase. There will be probably in the range of 70 million install base by next year and it would be hard to make that work.

DSi or New 3DS like new model is possible, but as others have pointed out, these types of revisions don't really result in a long term sales boost. They cause a short spike and then sales go back to where they were before or even lower.

They may as well just proceed for March 2023 for Switch 2 but they can support Switch for a while longer, the 3DS was supported with new software all through 2017 even though the bulk of it was outsourced projects (ie: Arzest doing Hey! Pikmin, Grezzo co-developing Luigi's Mansion, Mercury Steam doing Metroid II etc.). So the formula is basically already there.  

If you're not sold on a system after 6 years of releases, honestly you likely never were that interested in such a platform to begin with anyway. I don't think a console provider really has an obligation to bend over backwards that late in a product cycle if you're still not onboard. 

I'm all for phased transitions and maybe trying something different, but Nintendo has such a bad history with generational transitions that they're probably just better off not getting too fancy here.