The demo bigfoot did some years ago did already "solve" the issue of getting MorphOS to run on AMD64.
Putting a Linux kernel under it would widen the HW support with little to no effort, but there seems little to no taste for that kind of shortcut in the team.

Bigger issues not solved by using Linux (wether the kernel for an Amithlon clone or a whole distro to run QEMU):
- flipping endians around wich will either break compatibility or reduce performance
- getting minimal viability for users to adopt it and developers to port their SW when both are dwindling as it is
- moving MorphOS beyond single core/31Bit