My prediction is, as new members join, new levels of stratification will develop. There will always be the top tier which we see beginning to form now for a few reasons. The obvious cause is that they are top tier for a reason- they post a lot, and they are usually quality posts. This draws in more followers, and thus they stay on top. Another reason is related, though somewhat different. Due to the amount of posts they make, they are often the first people new users encounter. These new users are typically looking for people to fill up their feed, and as such they follow whomever they first encounter.

Likewise, there will always be the lower tier of people for much the opposite reasons as I just listed. While this tier of users may still post and comment, it will not be the same quality or quantity as do the top tierers. Some of this tier may not even post and instead just use hubski to follow people, which is fine.

I predict that intermediate tiers will develop. This tier will consist of people who post similar content as the top tier, but does so in a limited interest range. Obviously if someone is posting large amounts of quality content related to both science AND politics, they will acquire followers from both interest fields. However, if a user were to post in only one of these fields, it stands to reason that they would only attract followers from that field. It is these types of users that will make up the second tier.

What remains to be seen is if mobility through these tiers is easy, or if new users remain in the bottom tier unless they become superusers.