I hope HTC is still working on the transportation/supply system. Its been gone from the game a long time, and I think its one area where a "new and improved" version could be innovative and help the game, giving more targets and mission types for players to conduct.
I'm thinking about roads and RR tracks running between bases and strats, with tunnels and switchbacks used in mountainous terrain to keep grades realistic and reasonable. Bridges, big and small, all difficult to hit but destroyable. Truck convoys, supply trains, freighters spawning at sea and sailing into port, unloading into dockside warehouse districts next to RR marshalling yards, with two way train traffic on parallel lines running between ports and cities, that kind of stuff. Bomber guy and fighter-bomber pilot heaven.
This, this plus a well-implemented cloud system and enhanced explosion and damage graphics, get me excited about the future for AH.