One Possibility for a Rake Standard would be to set up the deposits for a particular site and float the rake in relation to whether or not the deposits are exceeding withdrawals and to what degree. This would of course be more applicable to the older centralized “rake-the-players” model, but nonetheless it might be useful for existing sites or as a thought exercise. The exact parameters might be debatable but it seems likely that as the field is expanding, and especially if at an accelerated race, then the rake as a % might stand to be increased, since such a field is likely to have more recs than pros. This is because there is only a smaller number of pros in the world than recs, and in a sense because it takes longer to become a pro (or a strong player). As the field starts shrinking or stagnates, or grows but only very slowly, rake as a % should probably decrease in order to facilitate growth. There maybe an equilibrium here and certainly there are other factors at play and so other parameters that could be set.
The centralization or decentralization of the poker site market is likely to be a higher level force here. A centralization (ie Monopoly) could change the need for and effectiveness of different types of rake schemes. It is the effective rake that is important here and that not understanding the relationship of the two with respect to the overall global market/player pool is likely to lead to distortions in our understanding of them.