Honestly, as a fan of the PSP game I would definitely like to see this become a legit fighter of sorts. I believe it can if the system is handled well enough. 012 is actually a pretty solid game all things considered its just a bit simple is all. If they allowed for a bit more complexity, and they seem to be by making matches 3 vs 3 ala MVC3, then we could be seeing some interesting combinations based on characters chosen, attack setups, and assists. It would be nice to have some new characters as well.(Secretly hoping Rikku makes it in)
Why would you secretly hope for that? A lot of people want Rikku in the game amidst FFX characters.
Speaking of which, I may as well speculate on new characters that most likely will make it in as playable:
FF2: Minwu, Borghen
FF3: Doga/Unei, Xande
FF4: Rydia
FF5: Faris Scherwiz
FF6: Sabin Figaro, Cyan Garamonde, Siegfried
FF7: Genesis
FF8: Seifer Almasy, Zell Dincht
FF9: Beatrix, Vivi
FF10: Rikku, Seymour
FF12: Balthier, Judge of Wings
FF13: Cid Raines, Caius Ballad, Sazh Katzroy