IF we get an ST emulator, it'll probably end up being just a plain vanilla ST emu, since so far as I know (I had an Amiga, and just watched the STE fuss from the sidelines) few games used any of the extra capabilities, like the larger palette (you're more than welcome to prove me wrong on this). It would be nice to have STE as an option, but if it had to be left out to get it full speed, it would be bearable.
Me, I'd love to see both these machines emulated ^_^ CPC & ST are under-appreciated machines, in my opinion.