Which civs would fall into this category?

Well, they may be initially nomads. Also hunting could have a little bonus (they might therefore have two or three scout cavalry at the beginning instead of one) and farming could be available only later after technologies have been researched? Not sure this woudl be changing much in the long run but it could nudge players towards a little different initial strategy.

nah i think decay is good. and yes,wonders are already territory root. this discussion is only about forts being root or not.. we are not discussing whether decay as a whole is good or bad

They definitely should be root territory, Wondeds as well. I’ve actually never felt like buildings that are inhabited by people should decay to Gaia, it felt a little strange. Buildings that are just storehouses and such? Yeah, they can be abandoned and stuff, but houses, barracks, stoas, etc? No.

I actually got the idea watching a game and remembering abt your mod having it.