I honestly don't think there's a snowball's chance in hell of this ever happening - at very least on current devces anyway. Maybe in about 5-10 years time? ;)
I don't know THAT much about emulators, but as already been mentioned, limited controls. Then you've got a different type of CPU - MIPS - to emulate... probably a big job. To make matters worse it's dual core...multiply the work by two, then maybe. Then you've got to allocate all the memory...32mb+ I think...as well as translate all the graphics functions and so on and so on...
It really is a very damn tall order... and as jcl says, we don't even have a fast GBA emulator yet, even though it has a similar CPU to the Axims and wayyyyy less difficult things to emulate.
In other words, I think you you can just go ahead and safely forget this idea for now... :) Why not just buy one anyway, for what it's worth..?
