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.
He did? Can you please point me to that post?
The only thing I could find about him commenting on adding the new rank after Legendary when he classified suggestions in
Community generated suggestions to improve the forum (+ eventual voting on them) post and that specific suggestion about new rank was in the "no" group.
Anyway, I really hope that we there won't be any new ranks as I don't see who would benefit from it. Maybe only people that are taking this forum way too seriously and wanna separate from others more than it is possible now.