I don't know...maybe I'm in the minority here (I don't think I am?), but I thought MvC3 was a pretty well-balanced game considering all the variables that have to go into balancing a 36 character MvC roster. A very large portion of the cast had proved to be tournament viable. Wolverine and Phoenix were the only two S-tier characters that really demanded heavy nerfs (and part of their overpowered nature was a direct result of how effectively they could leverage X-factor - which is another of the many balance variables the team had to take into consideration).
All things considered, they did a pretty damn good job on their first shot, especially with the rushed release date the team had to accommodate. Simply nerfing Wolverine and Phoenix, ironing out X-factor bonuses, and buffing zoning would have really rounded out the balance of the roster, but we are getting that and some other good-sounding balance tweaks in Ultimate. There are indeed some questionable balance changes (Doom, Zero, Wesker, for example), but I don't foresee any of the cast jumping up to Wolverine/Phoenix level S-tier now.
I could realistically see UMvC3 as having ~30 tournament viable characters, with the remainder being characters who are still highly usable at all skill levels below tournament-level, and a small handful of ass-tier characters (who will probably still be usable at mid-to-low level play). That's pretty damn good, in my book. There probably won't be many, if any, characters that are useless at all levels of play like there was in MvC2.
