Some things to think about for release 29 or 30.
1) Only buildings that can be captured are production buildings and Civic Centers. Any other building cannot be captured, including Houses that have "Fertility Festival" researched and Fortresses.
2) To compensate, introduce three levels of building armor classes. "Civic" or "Civilian" structures will have ~30% hack resistance. "Military" structures (Barracks, Stables, Arsenals, Elephant Stables) will have ~60% hack resistance. "Fortification" structures (Walls, Towers and Fortresses) will have a highest ~80% hack resistance. Pierce and siege resistance doesn't have to be changed, except for structures belonging to the "Civic" class.
This should massively simplify game balance and solve the Capture and Delete meta once and for all.