If we are talking shipped, I think it will get very close to 81m by the end of Nintendo's next fiscal year. So shipped would be in the April to June quarter 2021. OP implies sold through though and that will be in the July to September quarter.
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