As for the ground war, I had this thought just now:
Rather than introducing an FPS game for infantry, have each "Army" act sort of like a CV. Armies deploy from a new base type (Camp), which can also launch GVs. Going to the army takes you to the Command Post. From the CP, the player can either spawn in a GV from the "motorpool," or issue orders to the army itself (move to a position, entrench, or attack a position). Say, an army that's moving or attacking will be shown in groups of fire teams, say with riflemen, mortars, bazookas, etc. An entrenched army would have machine gun nests, entrenched riflemen, mortarmen, etc. I'd also give tankers the ability to "dig in." It takes so many seconds to go into effect, and once dug-in the tank can't move (except, obviously, its turret). A dug-in tank decreases its icon distance, making it harder to spot, maybe even earthen berms around it to protect it from enemy fire. In order to move again, the tank has to first take so many seconds again to take down its camo netting, sandbags, etc.
Armies can capture Fields, Bases and Camps, which would also be defended by AI ground troops (these defending troops would not be player-controlled). The number or availability of AI ground troops would be determined by the condition of troops at the base. IE, knocking out the barracks at a base means the base doesn't have troops available to defend itself (or deploy additional troops if there are already defenders spawned). Progress of the ground war would then be affected by these factors:
1) Directly attacking and/or defending infantry positions via air or ground.
2) Interdiction of supply convoys or destruction of supply depots.
3) Attacking/defending strategic positions (bridges, etc.)
The army would have a given number of troops. If enough troops are destroyed, the army is destroyed. The army is reinforced by supply convoys (which would launch from supply depots) or player-delivered supplies via air-drops, M3s, etc. The players would also be responsible for providing armor support to the ground troops.
Now, I would NOT eliminate the ability to capture bases via C-47s and other troop carriers. HOWEVER, bases behind enemy lines would suffer penalties, such as:
1) Unable to repair itself/doesn't receive AI supply convoys.
2) Random enemy AI troop spawns at the perimeter (you're behind enemy lines, do you REALLY think the enemy isn't going to try to take it back)?
That means that if players capture a base behind the lines, the PLAYERS have to take responsibility for defending it.
