I agree with the OP. Just talking calendar years, this year Switch will sell around 30m +/- 3m. In 2021, Switch is going to sell above 20m, and in 2022 Switch will probably sell close to 20m as well. For Sony, 20m seems around the peak they can do even in their best years, so they won't be above Switch in 2021 or 2022. For 2023, that is too far away for me to call. It could go either way. In 2024 and 2025, PS5 will be the top selling system. Then in 2026, PS5 will be a six year old system while Switch's successor will have built up a lot of momentum. So 2026-2029 will go to whatever Nintendo's next system is.
Basically the 202X years will mostly go to Nintendo. Sony will be on top for 2-3 years while Nintendo will take the other 7-8 (including this current year).
curl-6 bet me that PS5 + X|S sales would reach 56m before year end 2023 and he was right.
My Bet With curl-6
My Threads:
Master Thread, Game of the Year/Decade
Switch Will Be #1 All Time
Zelda Will Outsell Mario (Achieved)
How Much Will MH Rise sell?
My Bet With Metallox