Air and Earth are two opposing elements, and as such, should oppose each other.
Whereas Earth is protection, tanking your damage and killing you anyway, air is evasion, avoiding your damage and defeating you that way. Evasion through fog shield, through wings, and airborne creatures can already fly over iridium warden, but I think a buff to the airborne passive would give air more of a place.
Airborne creatures cannot be targeted by single target spells.
Firefly queen loses airborne.
There, air has it's theme of evasion, of flying over the enemies control, and sailing free and clear to victory.