I think that we don't have to worry too much about the Huge Hubskies making a hivemind- it could definitely happen, but after Reddit people seem to be very conscious of not moving things in that direction. There are definitely more and less influential users, but we're all aware of it and trying to skirt true power-users. One of the built-in protections from this is that you can stop following people, and if there's a backlash against a user/superusers then we can stop following them en masse. And if we don't stop following them, it's because we want to follow them! Seems like it should be a minor issue, but nothing that Hubski can't handle as it comes about.
I think the real problem will be quite the opposite. With the "ignore" functionality as limited as it is, one of the issues I've heard kleinbl00 talk about happening to Reddit is that there are so many users which can send you really offensive PMs, or spam your every comment with threats and name-calling, undermining your enjoyment of the site. I think unless "ignore" gets much more powerful, blocking PMs, automatically minimizing comments, I don't think Hubski has any protection from masses. It has a fair amount of protection from people you don't want to follow, but nothing for people whom you don't want following you. That's an issue.