Well considering the game is quite clearly going to be a SSB-inspired game, and there are SSB team members on it, it's not THAT out-there to hope that there will be legacy characters, but eh, what's the fun in just assuming every game will be **** until proven otherwise?
Also, Ubisoft is merely the publisher...Shitty developers can still publish good stuff (Ubisoft with No More Heroes, Sega with MadWorld, etc...)