I can't say how many, but there are quite a lot of voluntaryist/anarchist that continue to live in the US for whatever reason and just get by as well as we can. All it would take is the right conditions for them come out in the open. I think it's just a matter of the probability of negative consequences. Once that's low enough, we no longer follow the dictates of tyrants. I'm somewhat hopeful that such a situation could arise in the near future as the Government looses more and more credibility.