Maybe just limit it to people who comment, upvote and resteem. Then give the people that come later that are wanting more of a community in their realm, the option to gain new followers by commenting on their comments that they have a new follower and would like them to reciprocate or some such thing. "Hey, we should follow each other, since we're both here." Thread might get massive, but it may be beneficial in a sense to push it into 'trending' or even 'hot'. Just a thought.