I think people should be able to vote for whomever they want for TB without artificial limits like term limits.

As for moderators, of course TB has no purview over these sorts of things, but I think it would make sense to rotate moderators through different forums to avoid forums from becoming a reflection of the moderator(s) moderation styles with the goal being consistent and fair moderation. And if there are a lot of posters who want to serve as moderators then that rotation might include some time on the bench so that others might serve.