If we go with the fact that Anonymous is infact a true distributed environment, then the replacement mechanism will be very easy. I think Anonymous is a kind of humanized group-comm architecture sans a coordinator.
You're overestimating the uniqueness of Anon. Most communities nowadays don't have coordinators. And Anon doesn't have limitless communication channels, only about a dozen. For a site/software to be a good choice, it has to be already in the "hivemind". Ask 10 Anon tot tell them 10 places where they hang, and the most common choices are the (only) ones that are viable.
There is a unique feature though - the anonymity. This could really make a difference if things get serious.
