Not that other games are in particular need, paper mario is particularly not in need, due to its art style, theyve aged amazingly. Heck even in this trailer a lot of the environment has distinct polygon edges, because it was always intentional, its folded paper.
I guess sort of like the original Toy Story shouldnt ever need a remake because the plasticy old 3D look was intentional for a movie about toys.
Mmm i dont think its at all a static number. What matters is trimming it down to whats important. If you can keep bringing in new game mechanics, or exploring existing ones in new and interesting contexts, or keeping me engrossed in the story, it can go as long as it wants. Like, Chrono Trigger is considered a pretty short jrpg, because its very condensed for how broad of a scope it has, but boy is it a great game. Mario Odyssey got some criticism for how many moons are in the game, but i loved getting each and every one.
I wish developers took genre as gameplay elements and not entirely mimicing settings and tone and themes along with the gameplay. Lots of people were hoping AC6 could be a soulslike in a different setting, because no ones doing it.