If we manage to keep the dev tantrums/planned obsolescence at bay, all you will need, if the game devs or game engine devs are competent, is a lean elf(glibc)/linux distro: a set of glibc libs (interwined with the system ELF loader), the vulkan loader, libasound, a wayland compositor, and related linux userland interfaces.

In the future, we can expect a much simpler file format to replace ELF for CPU executables and dynamic libraries (ELF is beyond obsolete and overkill on modern hardware achitectures and its complexity is source of many issues), and maybe pure and standard GPU hardware command instanciable ring buffers, but that's much further away in the future, as we "don't know yet" (but we do for CPUs), and we still could get GPU vendor specific hardware command instanciable ring buffers (it seems this how the PS5 works).