It looks like the Arcade Edition of Super Street Fighter IV will be released as a DLC after all. A leaked trailer video revealing the DLC originally appeared on ConsoleTECH.net but was removed by Capcom from Youtube due to a copyright violation.
The Arcade Edition DLC will bring all of the four new playable characters. Yun and Yang, Evil Ryu and Oni. But that's not all, the DLC also implements the character balancing and an enhanced replay channel that lets player send their replay to other players. An Elite Channel that lets you watch the replays of other players with over 3,000 PP.