Lets face it first, this time air has to be done massively different from RD. Fighters have to com way closer to engage, AA has also a mutch mutch smaler effektiv zone and aswell, the speed difference between a Bomber and a Fighter is Massiv. So let's see what it needs to set up some nice Air fights.
Lets first talk about the call in mechanics.
I bett there will be zones from where the planes fly in, but this time it would be nice to see them return to this zone as well. Not just escape by pulling up like in RD. Remember, you can deep strike with fighters this time, and you kinda need it since you can not just call in a plane and fire a missile across the map. It would create a situation where you have to escort your planes back out of the map and even can draw in enemy fighters.
Don't fear the 'headon all day'.
This will not be such a problem, since planes will not be 1000km fast. Mostly it will e half of this and even lower after the first turns, you will have plenty of time to micro it and outplay your enemy by maneuvering a 2. fighter behind him. Also there were planes that were just 'better' in a face to face attack. So you will see more fighter types on the field.
Bombers and ground control.
Ind RD they were mostly just a call in suicide trade, thx to their massive firepower on point and the deadly AAs. Nothing like this we will see here i hope. In fact, we should split them up. Let's say we make a Heavy bombers department and a close ground support department.
To call in a heavy bomber, you need nothing. But you can't direct them on point. See them more like artillery strikes. Pick a Forest or a Town and select it for bombers. We are talking here about heavy He111 and alike. Once called in you can not change the target, all you can do is call an emergency drop which means the bombs are dropped and he flies away. They are slow so you will have the need to call in a fighter to escort them as well. See them more as an counter to Arty massing, which if on the map, will be mostly towed and not very mobile. And remember, there are no ground to air missiles and AA is really not that effektiv on this combat scale. so you can deep strike with them, until you run into enemy fighters.
The close ground support should be deadly, they should still be counter to a uncovered superheavy or an heavy resistance point. talking about stukas to drop pin point bombs in buildings, and 'Kanonenvögel' to lay waste on enemy tanks. But you should need a radio operator in the close area. If you have one, fine, call in the attack, change targets as you like and control the planes directly. Something like this will enhance the role of recons and commando units behind enemy lines, something the US Airborne can highly profit from to stop ze German Panzers.
Fighters dont rly counter them, something like a Thunderbolt or FW190 is a fighter themselves, you see enemy fighters you just run and be safe. This is where AA comes in handy again.
So let's see on the AA.
Don't make it deadly... Pls.. we have to face that a lonely 88 is not sniping planes across the map like a 9K37 Buk did. And a quad 20mm will not rape planes like a Gepard.. Heavy AA like the 88mm should be the counter to Bombers, not against fast moving fighters and ground attack planes. And even then you should need them in mass to kill. 1 or 2 scattered around the map? Should be useless. Massed, like 3-4 in a small forest, perfekt capable to hold off an Bomber. But even then only in a kinda small area around them. Make the Hvy AA capable to defend a Important location Like the 1 VP you need to capture where everything is focusing on. Or the mass of Arty you pile up in this liddell forrest. Make it expensive So people need to chose where to set up the AA strong point which is save but still fighters stay the focus of anti bomber action.
The small 20mm and 37mm guns? Don't make them rape bombers. or anything in fact.. Mostly this guns were used to force planes away from something not to kill them. And that's totally fine. They should be effektiv even in small numbers. Let's say a pair of Whirlwinds or simply 2 towed 4x20mm near your heavy tanks, you should be kinda save against ground attack planes. Make them in the style of the Shilkas. Let them stun enemy attack planes that com in so they can't bomb, but only with soft damage output. If he tries to attack you 3-4 times sure he's dead. But every time he will be stunned, saving your tanks and giving you the opportunity to call in fighters or stress out the enemy planes..
In fact, pls give planes space. they don't need to be deadly if they can move more freely on the map. Change them from the on point killers to more like a swarm of bees harassing your lines. This will even open the change of recon planes.