I don't think a Genesis emulator would be remotely possible. I do feel like there was someone working on an SMS emu, though maybe it was just individual games, rather then a full blow emu. But yeah, no 16bit system could run an emulator of the rival system. There's just not enough power for both the emulator & the games to run. I don't know if even the Neo Geo or maybe 3DO could run an emulator for any 16bit system, though I could be wrong.