One approach that might work (as has been posted before) is to go back to a points system for winning the war with only certain bases being capturable. As with AW in its earlier days these would be the central ones on the map. [edit: In fact, I will go as far as to say it would definately work.]
For example, you get points for captures, A2A kills, A2G kills (tanks, PTs etc.) and perhaps even kills but no points for aircraft with the wheels still on the ground. You can structure the point awards so that shooting down flying aircraft is just as important to victory as capturing what may be an undefended base. Having a limited selection of capturable bases, centrally located would also concentrate the action more. It is a mode that, IMO, worked very well at promoting combat.
It was changed in AW around Gamestorm because with the increased number it stressed the existing AW netcode beyond its capabilities (as Moggy told me. I believe the limit was about 60 aircraft in one area and the smaller/older "central neutrals" maps would have stressed that regularly). However, AH has better net code, and with a larger map, and a larger group of capturable islands you could still spread out the action but have some degree of concentration beyond what we have now. [edit: I doubt it would stress AH netcode beyond the current "final bases" period of a capture]
All countries would, in essence, fight over the same 20 bases for the tour, with the points totaled at the end. Not a new concept obviously

but one that worked very well and could work well again, IMO, with the right balance of base numbers, and point awards for activities. You could even make strat targets important from a points perspective, if not from a gameplay/role perspective, etc. Same with truck convoys and barges, etc.
The downsides would be change (always scary); extra programming (points tracking database); adding new maps (current maps might be difficult to work since you want carriers to have a role); intellectual property isses with the AW game model?; and fine tuning the points to get varied gameplay.
Charon