That's very cool. I'm not sure you're going to come up with anything better than just having new users follow those who are on the community page as top commenters/recently badged, etc. Works great.
Actually, what I'd like to address is the feeling of a hole in the middle between unshared posts and popular ones. I can appreciate that some people are browsers, and I think we could improve the breadth of posts that can be perused for new content or people to follow without watering down the overall experience. We will see if I am right.
Yeah, I know what you're talking about. Currently, once you have pretty defined what your info bubble looks like, it's hard to really break out of it :) I'll state from the beginning that as a user, what I want in terms of discoverability is to see things that are popular (or seeing intermittent popularity) to other people, but that do not fit within my self-built echo chamber. The way it is right now, if a post is good it will not stay in the unshared section for more than a few minutes. However, if it's not shared by someone with the followers to get it out there and exposed, it'll languish without any real exposure. At least, that's the impression I get.