I think I have a solution to this, something I called Reddit150. You have divisions, like in soccer or american foot ball leagues, where the highest rated members can be promoted to the "higher" league and also demoted if their contributions are not good enough. People from a lower division cannot comment on a higher division, but everyone can view all divisions, this would result in situation where the media would always reference /r/science from the Alpha rankings for example, the prestige of maintaining your position would ensure a higher quality of content at all times. I called it Reddit150 because that is a typical number of names a human can remember for our social structure before it starts to breakdown, the member number in each division number would have to be in the order of 150k or possibly something that adapts with the total user base.