Well,
HTC has made it clear they are primarly running a FLIGHT sim. With some land and sea stuff to add variety interest (and targets :-).
I wouldn't get my hopes up to see a vast profusion of different kinds of land vehicles.
I will say, though (this is purely my educated guess) that I'm fairly certain the next perk to be announced will be a Tiger or a King Tiger..
Perk points are divided into fighters, bombers, and vehicles, and you can't switch them around.
And the Tiger has been specifically mentioned by Pyro as an example of a Perk vehicle.
They have 1 perk each for fighters and bombers....I should think they will want the vehicle people to have something to use those perks on.
However, I really wouldn't expect more than a T-34, some variant of a Sherman, and some sort of British tank anytime in the forseeable future (Again, this is purely educated guessing on my part.)