2023, here's why.
They will release some kind of power upgrade, probably in 2020. That will give the Switch a longer life. Plus, Nintendo tends to have a 5-6 year life cycle in between one platform to the next. With how successful the Switch is, it will be in the 6+ years category.
They also need time for a lot of successful Switch games to get sequels on Switch. Super Mario Odyssey 2, Breath of the Wild 2, Super Mario Party 2, Mario Kart 9 (sequel to a game that was ported to Switch anyway), Splatoon 3, etc. I think we'll get the next Smash in 2024 for the 25th anniversary, but that would thus be on the Switch's successor.
The 2023 release date would probably be March (Switch release month) or November (the industry norm).
Lifetime Sales Predictions
Switch: 151 million (was 73, then 96, then 113 million, then 125 million, then 144 million)
PS5: 115 million (was 105 million) Xbox Series S/X: 57 million (was 60 million, then 67 million)
PS4: 120 mil (was 100 then 130 million, then 122 million) Xbox One: 51 mil (was 50 then 55 mil)
3DS: 75.5 mil (was 73, then 77 million)
"Let go your earthly tether, enter the void, empty and become wind." - Guru Laghima
