The only restraining feedback loop I see atm is that the value of an upvote has fallen dramatically in the last few months - in percentage terms of SP it has gone from about 0.02% to 0.007%, but on payout (assuming 50-50) this almost doubles to about 0.012%.

On chainbb, being a forum, posts are bumped every time there is a new comment, so the front page of each sub-forum has a mixture of new stuff and the most discussed articles. One quite simple solution on Steemit would be have another category: trending, new, hot, promoted aand discussed.

Of course, we will then see the auto-comment bots rise and a new game-cycle begin.

In essence, any encoded rule must (should) have a built-in negative feedback rule. If it doesn't, then the game will spiral towards some attractor that may limit its profitability at the global level, such as a steep rise in recent_claims and fall in reward_balance.