well i think adding something like combined arms would be cool for the Wehrmacht. Mechanized doctrine for me is the one i use to spearhead assaults so i would love a tech tree that gives me some Luftwaffe support besides stuka dive bombing. Of course there could just be a whole new Doctrine that is just all air and focuses on recon, resupply and some air strafes. The Defense doctrine feels like it needs some more Arty or maybe a big mortar. could also add a bunker with anti air flak guns i mean that is optional because when ever i shoot down a plan they always crash into something valuable anyway. For Tank hunter i really don’t know. :O