Axis v. Allies will be a tough sell. Not just for political reasons, but because not all countries are well represented throughout the timeline - like, there's nothing pre-1943 for Russia. Most of the IJA stuff is either pre-41 or post-43. Rolling plane set would work, but not with historic country alignments.
There are definitely holes in the plane sets that would have to be filled. Your absolutely right on the plane sets.
I think the "political reasons" is not much a factor. Surely you don't think just because someone fly's a 109 they are Fascist and Anti-Semitic? Or a La7 pilot can't wait to join the "party" and turn his neighbors over to the NKVD or send millions to their death in a purge?
Fighter Ace, a very cartoony game with a ridicules flight model, does just fine offering only country specific sides.
Warbirds with it's even worse flight model, 2D graphics, and plethora of bugs has hung on offering just a Axis vs. Allies main arena for a long time.
In fact, the only reason WB's has been able to survive is it's loyal following in the AvA Main Arena.
Historic country alignments make sense both with the market and the game.
Now there would be some whining as folks could no longer log on and fly their favorite late war Uber fighter all the time.
I think though that as folks learned that every time period had it's "uber fighter", encountered a greater variety of planes to fly, and fight a wider variety of enemies...The benefits would far outweigh the detractions.
Very few "pilots" in AH outside of the CT or scenario players, know exactly how good a fight you find in a 109E vs. a Hurricane Mk I! Some of the best fights in the game are the early/mid war match ups you rarely see in the MA.
Crumpp