I don't see any connection between Vampire and MorphOS.

If you want just run some old Amiga games you can use UAE/WinUAE, if you love old 68k systems you can buy some 2nh hand old Amiga model or the new Vampire V4.
All choices are good and can be combined simultaneously!

About next MOS development rather than generic x86 PC, I'd like to see it on Arm RPi or eventually on old x86 Macs.

Anyway maybe first step before change arch could be 64bit extension and later AMP/SMP support.
Other critical aspects are more modern GPU support and in general today's common peripherals drivers.