x86's days are numbered.
I have been hearing that since maybe 1998... sigh...
It seems to me Amiga users/devs don't want a true new OS (I mean "OS", we shouldn't care at all about the hardware) but are more interested in running old stuff.
As I see it, the question is simple: do you want something new, taking advantage of new hardware (no matter if it's x86/ppc/68k/arm/big/little endian), powerful, fun to use, future-proof ? Or do you want to run your single-threaded workbench, display your nice png icons, and play with your scrollable screens ?
Just answer the question. If it's the second, no need to even talk about new architectures...