I sorta put PS5/XSX games into different tiers
Tier A (games that probably barely run well on a PS5) - Alan Wake II, GTA6
Tier B (mid-tier games) - Final Fantasy VII Rebirth, Spider-Man 2, Ratchet & Clank Rift Apart
Tier C (games we know run on a PS4) - Spider-Man Miles Morales, God of War Ragnarok
Tier B and C I think will be doable on a Switch, Tier B will make you sweat though to get the game running well.
Tier A ... probably some devs will give it a shot, but those will be really hard to port, it'll be kinda like the current Switch trying to run Witcher 3 or Batman Arkham Knight.
I don't think there's going to be as many Tier A games though period, just because they're so expensive to produce, so there is that aspect too.