Perhaps what is needed is a bit of a redesign of the way that "bases" are set up. Currently, we have vehicle bases and ports that just need to be de-acked and have troops brought in, as well as airbases with towns that must be de-acked and "white flagged" before troops are brought in.
What I envision is something a bit more like this: Instead of bases being the center of attention, there are population centers of various sizes. The current town-sized population centers would just have a base or two, perhaps a vbase and a fighter field, or a lone midsize airfield, or a port and a vbase, etc. A larger town could have three or four fields in various combinations, and then there would also be little cities, that could have up to and including a large airfield, two small airstrips, two vbases, and a port. The purpose of these bases would be to defend the population centers: a larger town/city would logically need more bases to defend it. The strats would stay largely or entirely the same.
This is just the kernel of an idea, there are numerous details to be worked out. I just think that it would be a good change in a game that I often hear complaints of stagnation about. This change would have several positive effects, including being much more realistic than the current model and the fact that it would be a total re-working of the "win the war" strategy, which would bring novelty to the game.