There are only two version of PC, 32 and 64 Bit. So yeah porting to 64 bit means it is future OS compatible. Because Windows 10 after 2021 may not be 32 bit available so yeah games and apps are being ported slowly.
Fan-made Mario 64 PC version enables native 4K resolution and ultra-widescreen support…
www.videogameschronicle.com
The fan-made port, which was first shared on social media sites this weekend, was made possible by a 2019 recompilation project which saw fans reverse engineer the game’s source code.