I don't know what we're supposed to do with it, except Bryan's point not to discount the probability of something happening.
Anarcho-capitalism is a "crazy" idea (in the way that Bryan is using the term). Totalitarianism, state socialism, theocracy, and monarchy are also "crazy" ideas (not everywhere, but I assume we're talking in the U.S.). Indeed, Bryan even points out that some of these are today considered "crazy" where they wouldn't be a thousand years ago (when democracy would be considered "crazy").
This is why I am struggling to see how this helps the case for anarcho-capitalism. If the message is only "don't count it out", then OK - message received and I agree. I don't count out a state socialist or a totalitarian future either (hoping that's not our future - but I could see it in 3013).
I guess I just don't see what overcoming the plausibility hurdle really does for anarcho-capitalists. The real problem is the advisability hurdle, right?
That said, I don't think this clearly does away with the plausibility hurdle (although it helps). Anarcho-capitalism has a problem offering an explanation for one thing that totalitarianism or monarchy or feudalism/warlordism don't have a problem with: it seems like it should be a highly unstable equilibria. Totalitarianism, monarchy, feudalism, state socialism, etc. are "crazy" equilibria but at least they should be somewhat stable in the short-term (if not the long-term).
It's hard to conceive of what would make anarcho-capitalism a stable equilibrium even if it were a plausible equilibrium (which I agree it is) and even if it were an advisable equilibrium (which I don't think it is).