I have read a bunch of discussions on this matter over whether SSFIV will have downloadable characters; personally, I doubt it. There have been the odd mentions of Yoshinori Ono talking about such an event, but this set-up makes little sense - at best Capcom would have to compete with their own branded DLC, like costumes, at worst they're splitting up the Street Fighter [IV] community in providing another alteration in which the game can be sliced up, as I'm sure at least one-million players from the original won't be coming over to Super.  
 
Tournament play out of the question, it would still require a hell of a lot of data to store these characters as downloadable objects - Ono has rather much confirmed there are no other characters on the disc to unlock, unlike the costumes, so it would need to be all new data. Street Fighter IV models are extremely high-fidelity and to match the rest of the cast would take some extreme storage space, in comparison to things like costumes. At which point, Capcom can of course not bundle characters - it wouldn't be worth the time or effort if they did. Then again, if they were to offer one character in a pack, who would that be? I can't imagine who would be popular enough to put out there as a standalone character, Ono has been talking about obscurities like Hugo and as much as I love that character, I doubt that Capcom would be prepared to put money behind that as the development team's current project. Soulcalibur IV did this with Yoda and Darth Vader, but these characters are extremely well-known in popular culture terms and it is quite a bizarre comparison to any prospect of Capcom releasing constant one-ups to the SSFIV cast. 
 
So I suppose the likelihood of it comes down to the possible conundrums one would face in handling this kind of project - how could Capcom possibly profit from it, who would actually pay for it and who would have the space or patience along with all the other downloadable content? It makes far more sense to package it all into an 'Ultra,' 'Turbo' or 'Bunghole' edition in 2011, where they can again charge around half-price and make money back on costumes or that ilk. RANT GET.