IIRC, Theymos has hinted about adding at least one new rank, and members have chipped in with suggestions for name and customization,big however this should happen, then besides an activity count there would also be a new merit requirement that one should reach to attain this new rank.
Would be news to me, I'm pretty sure theymos has never commented on further ranks being added, I could be wrong in that though. I think other staff might have hinted at supporting the idea.