You know I would love if they took the moves and characters of Street Fighter 4 and did the HD 2D treatment of it if they thought they couldn't pull of the 3D graphics correctly...like they suggested with the HD remix thing.
Actually, I think it would be pretty amazing if they did a 8 Bit style Street Fighter game, but with still 6 button controls...it would be funky and crazy and fun.
Or just take all the Sprites from like the Dreamcast Street Fighter, Darkstalkers, and every other Capcom fighter and merge them into one fantastic game...I would not care if the balance was off...I think it would be fun.