Maybe a good solution is to break the community down into neighborhoods of ~150 people.
The big question would be how to propagate submissions and comments between communities. Especially if each community develops its own unique character. I've thought about organizing each community onto branches of a B-tree and letting upvoted submissions move up the tree, though my intuition says that this might not scale, as one community might overpower the rest.
Anyway it would be interesting if someone builds it.
It felt weird that a satirical website would have such a profound article; it's good to know that more serious consideration into the underlying concept has been made. (The above wiki article once made heavy reference to the term monkeysphere, but had it edited out over time. There's still quite a bit of text about it on the discussion page.)