I'm thinking a card similar to the Factory/Airport, I touched on it in the other post I made, this one is actually a bit more thought out. A card for a Field Hospital, something like 100g, because honestly it's pretty powerful. A ground building that heals adjacent units for a certain amount of HP per turn, up to a maximum of 3 adjacent units. at 100g, I'd say like 5-7 ish HP per turn would be balanceable.
I think it would be nice if you could use the evac cards in tandem with something like this. rather than evacuating your unit back to your base where it sits until it can get picked off, you could evac it to a field hospital instead where you can leave it until it's healed up.
In a two-for one move, this card could also be the airport equivalent for infantry. It could produce either infantry only or infantry and recon.
I like your idea
you should post it at "Create a card contest"