Seeing as we've missed quite a few opportunities to reveal the Ice Climbers through PotD's, I think they're saved for E3. They've been starter characters every time so far, and I think they'll stay like that in this game too, so there's no reason not to reveal them before release. This month doesn't have anything going on for them though (and we don't know if we'll even get any more character reveals before E3 - if we do, I think MetaKnight and Wario are the safest bets anyway) and an E3 reveal would be good for IC's, especially if they've been changed drastically or even a bit (seeing as they did have problems on the 3DS) so that can be discussed about, sort of like they did with Sheik and ZSS on the Smash Direct. That's the only veteran(s) I'm expecting, but I think we'll see one or two more, especially if none are shown this month (hopefully Snake is one of them).
As for newcomers, I truly wish for Ridley and Mewtwo, since those two are on very questionable grounds at the moment (the former especially). Pac-Man seems to be a more "realistic" expectation, but for some reason I'm not 100% betting on it just yet. I don't know how many newcomers we could get though, but I'd be more than satisfied with those three. Or a Paper Mario reveal of course (that alone would let me die happy).