i actually don't think it would be that long, judging from what smea has already achieved, he already must have a pretty stong basis for the development, once released i would say emulators would be some of the first thing done....maybe basic but still an emulator, if i remember correctly the psp had a gameboy emulator pretty much from launch
I also don't think it will take that long, but I think it would be too bold to give a shorter estimated time, since 3DS homebrew scene is giving it's first steps by now and I don't know if there will be any difficulties in doing a SNES emulator to 3DS, especially a full working SNES emulator. Special chip catridges have always given headaches to emulator developers.