If AA on the ground has just as much chance of shooting down a jet as the jet does of taking out armour, then they are balanced. But if ground vehicles are vulnerable to other ground vehicles and anti-tank weapons and aircraft, but aircraft only really have to concern themselves with other aircraft and can attack ground targets without a care in the world (like in BF2) then it will be a disaster.
I'm surprised nobody's waded in with cries about 'realism' yet, but if you want to play realistically then all the infantry should sit around looking at porn until the air force has destroyed everything, then the infantry can stroll in unarmed and put the flags up.