The Street Fighter franchise has a reputation for tacking on inscrutable modifiers like Alpha, Super, Tournament, EX, Zero, etc, in lieu of full sequels. The game's producer says Super Street Fighter IV is as far as it goes for this generation.
Yoshinori Ono told Official Xbox Magazine he has "no intention of carrying on 'Street Fighter 4' into 'Hyper Street Fighter 4' or 'Ultra Street Fighter 4', because I'm aware of the mistakes Capcom has made in the past."
"So whether it would be a different IP or another Street Fighter, we'd like to keep options open. But in terms of Street Fighter 4, this is definitive... Super Street Fighter 4 should be the distinctive end."
That does not rule out DLC for either title, of course. "But as a packaged product, I think this is the last," Ono said.
Street Fighter IV Games To End With Super [MTV Multiplayer]