I'd like to note a connection between Vladimir's idea, and Robin Hanson's moral philosophy, which also involves taking into account the wants of counterfactual agents.

I'm also reminded of Eliezer's Three Worlds Collide story. If Vladimir's right, many more worlds (in the sense of possible worlds) will be colliding (i.e., compromising/cooperating).

I look forward to seeing the technical details when they've been worked out.