Since its going to be "experimental", can we try a world where Murder is disabled. Leave all the other stuff like siege, vandalism, theft, etc.
I want to see if we really will get uncontrolled anarchy or if this one change will help retain more players.
Edit: The point of this suggestion is to try and raise the lower bound on what players can lose. Players would only be able to lose the stuff on their character while out in the world, thus lessening the perception of loss via player interactions. This would hopefully lead to a slower player loss over the world's life cycle.