It's got to be 2021. This year is already tracking ahead of 2020, which means it is doing better than the Animal Crossing + beginning of COVID lockdown months. With a new hardware model + Pokemon, Switch is definitely going to be higher this year. At the same time, the momentum this year is only slightly higher. Switch's sales growth was really rocketing up in 2019 and especially 2020. It's not doing that this year, so I think this is going to be the peak year.
Next year will be down slightly, but it will still be high (probably 25m+) due to a bunch of solid software releases. That is why anyone saying Switch 2 is coming in 2023 just has no clue. Imagine Nintendo saying this in 2022. "Hey we are having one of the best sales years that any system has ever had. Why don't we kill off this goose that is laying all of these golden eggs...." Nope. That ain't happening. So while I think 2021 will be Switch's peak year, I think every year 2022 and on will only have mild drops in sales giving the Switch a very long life.
Isn't this exactly what happened in 2010?
FY ending 2010 DS sold 27m
FY ending 2011 the 3DS was out in Japan (shortly to follow elsewhere)
This is what DS shipments looked like by fiscal year, where 2008 means FY ending March 31, 2008. In FY2008 they shipped 30.31m units and in FY2009 they shipped slightly more 31.19m. That looks like what is happening last year (FY2021) and this year (FY2022). This year is selling slightly higher than last year. So lets continue this analogy.
|DS FY||DS Sales||Switch FY|
The 3DS launched right at the very end of FY2011 (Feb/Mar 2011). I put in the next fiscal year to show that DS sales were obviously dropping like a rock at that point. This means that if Switch sales actually do fall off a cliff, then the earliest release for a Switch successor is Feb/Mar 2024. A 2023 release date is unrealistic even in the most pessimistic scenario. And if the Switch has gradual drops in sales, then it will release holiday 2024 or later (most likely later).