Anything is possible. It's a question of whether or not it would run at an acceptable speed. Dreamcast at 50% is well beyond dreaming. You'd be lucky to get frame rates that reach whole numbers.
He needs to update this list. The Genesis is out of development, and I'd say that the SNES emulator is out of the early stages of development, because it works pretty well. Also, I disagree about the Nintendo 64 being playable on the iPod/iPhone, because it's barely playable on the PSP!