The GPU would also be a problem. I don't think the Wii/Gamecube's GPU block really corresponds to any ATI/AMD card.

What you could probably do is take a Wii emulator like Dolphin and virtualize the CPU. Basically combine Dolphin and KVM_PR, getting ~native CPU performance while still needing to do 3D translation and simulate the IOS side of the Wii.

(Wii games run with the CPU in the supervisor state IIRC, so you can't just run them as processes under an OS, you'd either need a proper hypervisor or to catch traps caused by running supervisor instructions in "problem state", a la KVM_PR.)