Generally before a console announcement a lot of rumours and leaks happen in the months before. At the moment there has been very little said about a switch successor so I feel like this year is unlikely next year maybe.
Yeah. The leaks about a potential Switch successor launching in this recently started fiscal year are pretty slim and could easily be fake. Nintendo would have to be super good at hiding dev kits, images, and other things if the next platform is already out in Q4 2023.
Switch may have only been officially unveiled on October 20, 2016 (less than 5 months before launch) but Codename NX was confirmed in March 2015 and the March 2017 release date was confirmed in April 2016. That doesn't mean the next system is still 2+years away, but rather that we have to hear something. And it seems the only reason Nintendo confirmed NX so early on is because the 3DS was already 4 years old that point and the Wii U was a failure that would've been really tough to turn around at that point.
It's against Nintendo's interests (I would think) to announce a new system is in development (with a codename or unveiling) too far in advance. The Switch is declining year-on-year but has still been a a mega-hit.
Whether Switch hits 160 million or above, I'm pretty sure 2023 is the last year it sell 15 mililon+. And if the successor launches in the first half of 2024, Switch probably won't even sell 10 million in 2024 (see my earlier post about sales decline for even the DS when it was replaced).
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: 67 million (was 60 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