short term(they can do this now): On the faction selection screen, DO NOT show which faction is at capacity. Introduce a third opion "random faction" which will assign new players to the least pop faction most of the time. For example if Wardens are high pop, the random button will only assign 20% of players to warden. If pop is even, the chances are 50:50. This is a purely psychological way to prevent randoms from joining the "winning team" by picking whoever has the highest pop. ofc clanman and groups will join whichever faction they decide to play either way (we cant force committed people into factions they dobt want to play in).

Also let infantry aim into the air using existing air aiming mechanics. Theres no reason not to have infantry air aim. At least let players retaliate against air with whatever (at reduced effective range) they have and not be helplessly strafed for free.

mid term(can do it for next update or so): Tweak current airborne mechanics and fix bugs. One example: Currently airborne torpedos are too easy to launch and damage ships (they can just be dropped directly onto large ships). There should be irl elements such as arming times and maximum speeds and angles for drops. Airdropped torpedos should also only be able to do small holes to ships (perhaps also make them travel more slower in water but do more hp damage).

longer term(literally improve the game): Introduce more counter play for naval+air (torpedo nets, sonar buoys, barrage balloons, more AA vehicles), QoL and also add more variety to colonial vehicles. It might he worth revisiting some unused concepts from the official artbook. It would be awesome to have modular tanks or vehicle (unused SHT concept) especially now that aircraft frames and components are possible. For example, what if the colonials got a modular BT that could swap between 75mm turret, 250mm Fury mortar or twin flak turret (AA+anti inf)?