After much deliberation:
3'8M Switch (probably going full year at $300 with maybe some discount in the process, possibly peak year for Switch in Japan)
1'4M PS4 (no price cuts are going to stop sales decline this year, i expect a rough 2nd half of the year for PS4 in Japan)
Peak year at it's original price seems like a contradiction in my eyes, I think Switchs peak year we will see some sort of permanent price drop. It could very well be the peak year, but not without some sort of pricecut.
I'll chicken out and wait for w2 to see how it goes before a precise prediction myself ;) But as far some discussion goes... Assuming AC and Pokemon gen 8 are actually both coming this year in a timely fashion (more like summer+holiday) compared to 2 x holiday releases like this year I'm confident we'll see 4M+ for Switch.
I dont think no pricecut can save PS4 from dropping a bit more this year, KH3 is going to push some consoles but not in a way MHW did. 1.3-1.5M would be my earliest of guesses.