I liked the idea a while back where new clans sort of piggyback on current clans. You can only unlock this clan say if you have all the commons of the certain clan.
Also I like the idea of ur2 as fr was a let down for me. I love the idea of crs leaving to go to that city and that you can only get to that city if you are a certain level
Clint City Government
A Desert/Wild West Clan
Classical Style Clan (Roman and Greek Warriors and such)
Cult Clan(more demonic than alien like sakrohm)
The Plant People clan is actually neat sounding have the environment fight for itself could work in with that sewer idea