Yeah 2023 sounds about right; give it 6 years before replacement, 5 would be cutting it too short for such a successful system. 

I'm not going to look up posts from 3 years ago but I do remember reading it from a few users.

It obviously wasn't the general consensus, just trolls and the vocal minority.

Yeah March 2022 seems way too short. March 2023 seems reasonable. We're probably gonna be getting a second round of major titles on Switch (Mario 3D, Zelda, Pokemon) from holiday 2020 thru 2021, so Switch 2 coming out in Spring 2020 would mean none of those first year for Switch 2 and I'm pretty sure they're gonna want at least one of those on launch year after seeing how big Zelda and Mario were for having a great first year for Switch.

I also agree with a $350 Switch 2. If releasing ~2.5 years after PS5/Scarlett at a higher price point than Switch allows Switch 2 to get close enough in power to those systems to play graphically downgraded but still good versions (lower res, lower fr, some missing effects, but otherwise the same game) of next gen 3rd party games that would bring back a sector that Nintendo hasn't had in 3 consoles. Plus Switch isn't a small handheld that can be slid into a pocket, so Nintendo has proven the space for a handheld you have to carry in a case or slide into a backpack or whatever, so I could see them making a slightly larger Switch 2 at a little higher price point that can pick up good downgraded versions of all but the absolutely most intense multiplat AAA 3rd party games on PS5/Scarlett.

I expect Switch would still get minor support for holiday 2023 and then Nintendo would focus 100% on Switch 2, so I think after 2023 Switch would only sell some 5+ million, though that could still put it at 115+ million lifetime. I think PS4 will end up just over 130 million, and Switch should end up 15 or so million behind it.

If that was even remotely true, then the opposite would also be true, meaning that when the Switch entered the market, the other two's sales would have faltered. But instead, they had their best year in sales!

Switch, and Nintendo by extension, is a wildly different market with a different appeal to Playstation and Xbox. You can see it with the sales numbers, too: Playstation plus Xbox always add up to something around 170M per generation, but Nintendo's sales are all over the place. The reason is that Nintendo is notexactly competition to the other two, but it's very own thing. You don't buy a Nintendo console for the same stuff you buy a Playstation or an Xbox. Instead, it complements the other consoles (and/or a gaming PC), not compete with them.

Well, then you should also see the problem with your prediction: RFA is selling as fast as it can due to stock, so sales will not falter nearly as much as normally after the holiday season and further down the line.

If you want to compare it's sales in Japan, I guess Splatoon on the Wii U is the best recent example: A surprise hit that caught Nintendo completely unaware in japan and where they had big problems supplying enough games to the market to satisfy demand. Ring Fit Adventure is living through exactly the same scenario right now. And I guess the situation is similar (if less "dire") in other countries, too. I guess we'll have to wait for the next QR to know for sure, though.

Yeah March 2023 would be the best time the way I see it. Wait for Switch 1 to reach its proper sales potential, and for mobile tech to get to the point where Switch 2 can be to PS5/Scarlett what Switch 1 was to PS4/Xbone.

It will probably be 7 rather than 6. 7 years is the norm now for consoles. The former president Kimishima stated they intend to support the Switch longer than the 5-6 year lifespan (stating perhaps a 7-10 year lifespan). 7 is the safest bet so likely March 2024 or Holiday 2023. 

Here's the quote: https://metro.co.uk/2018/02/02/nintendo-plans-support-switch-7-10-years-7281632/

I think the PS4 will end up doing around 125-130 million and the Switch around 105-110 million.

"Support" doesn't necessarily mean "not replace" though; 3DS has replaced after 6 years but still got support in 2017 and 2018 after the release of the Switch.

I don't think that a person that though it was good to go from PS4/X1 to Switch would be much worried that PS5/X2 released. They have bought Switch not because it was more powerful, but either because it is portable or because it have Nintendo SW.