The earliest possible release at this point is Q4 2023. If it was launching in any of the first three quarters, it probably would've leaked or been announced by Nintendo. But I'm banking on Q1 2024 still, just in time for Switch's 7th anniversary.
Then again, Switch was officially unveiled less than 5 months before its release date. However, there was Codename NX that was confirmed to launch March 2017 many months before the Switch reveal. And NX was first name dropped around E3 2015.
Nintendo is soaring high right now, so they don't need to announce a codename or reveal a long time in advance. Q4 2024 is quite possible, and I suppose so is Q1 2025. Anything past that and I will be shocked.
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
