We have a maximum of 9 possible characters being profiled before the game is released in the U.S. if they do 1 character a week (with there being a second character this week to make up for none less week), but the main problem is that we don't know whether the game will be released in Japan first...(The site STILL doesn't have the Japanese date up for some strange reason...)
Right now we have 20 characters (I'm not counting ZSS as a separate character, as she won't have her own select icon), so I'll say we bump that down to a maximum of 8 to make a nice even number...Of those, the vets I'm sure will return are
Captain Falcon
Jigglypuff
Ganondorf
Mr Game & Watch
I'm still holding out for Marth, Ness, and Luigi to be unlockables, and I'm going to assume that clones are gone, and that Mewtwo is gone (again, there's no evidence that he is, I just think that Lucario could replace him as the powerful Pokemon...)
This leaves a maximum of 4 possible newcomers...(I'm actually quite confident that we'll get 3 more before the game is released) Of those, I'll say we get these:
Animal Crossing MC
Olimar
The last guy could be anyone, but I do feel as if the AC MC and Olimar will be present from the beginning to represent their franchises...
(Edit: Ah crap, I forgot that Snake is going to be an unlockable, so that could make for 5 vets and then the 3 newcomers...Augh, this speculation is so useless...)