Zoning doesn't suck that bad in MvC3-- that is, it depends on your setup (of course), and the matchup... On the flipside to that, rushdown ain't all that either... You've got some flyers but its not crazy triangle rushdown like in MvC2... Air dashing isn't gonna make that worse either... If anything, air dashing can help some characters escape and get space, especially if they don't have a dash at all, or its jacked up and slow like Doom's dash...
Real talk, I could bust out Doom, Arthur, and Task and zone all day if I wanted to... It's not gonna work on all the matchups though... Also, I believe the stages are shorter length-wise, so zoning isn't gonna be the big thing that it was in MvC2...