I quite like the idea of the Autobots only being ground based, a bit like the original toy line, while the Decepticons have the advantage of flight. I know Jetfire had an air-based alt mode, but as in G1 he started off as a Decepticon. So given the amount of new Autobots we've already seen, I'm fine if we don't see either of these in TF3.

It's quite interesting that this was alluded to quite a bit in G1 at first, with them creating the Arielbots as if it were a major step for them to have flying alt modes. Later fiction, however, made it seem like air-based Autobots and ground-based Decepticons had always been the norm. But I digress...