X86, but it's the OS'es that must be completely ported to X86.
The goal should be that 3.1/3.5/3.9/4.1 run entirely on X86, if we accomplish that, then Amiga as an OS has a future again.
It shouldn't matter which hardware would be in it, but modern drivers should be devolved of course.
I expect the OS to fully run on a X86 on a SATA SSD with whatever video car, audio card/onboard, network and everything else.