I'd seriously consider a subscription fee if I could get access to a good stable server with people who have microphones and and some sort of chat program. I don't know about $15/month like we have for AH, but anything less than that that would put a fair dent in the owner's upkeep costs would be great.
I always preferred playing the game online because I liked how I could see other people's work and be able to cooperate with them on large projects, and I never had any motivation to try to build something cool if someone else couldn't ogle it while I check out their stuff too.