For the sake of both preservation and playing them on decent hardware that people actually like, EVERY Wii U game worth playing should be ported to Switch eventually.
I think it could be a problem for the Switch in ways it hasn't for PS4 because of the difference in userbases.
People are used to there being a Playstation version of just about every major game, and its part of their expectations for the brand.
People are used to buying Nintendo consoles for exclusive content.
Port-able indeed.
This.
Also this. PS4 has a ton of ports and it does fine.