Yes, there's some handwaving about private entities - which in practice become de-facto small - scale governments of limited power and scope. But if the US suddenly became a libertarian paradise, something would still have to act as a de-facto state to deal with the threat of invasion from places that were not. And immigration on a large scale, by people who are not willing to integrate / buy the land, but simply take it on their own, via their own army, or however else, IS an invasion. Much the same way the US and western nations are being invaded now, aided and abetted by their own governments.Looking back at that post I realized that there is a fictional setting that deals with this - Mike Williamson's original "Freehold" novel, which is often described as a libertarian utopia.
It deals with the issue of dealing with the Earth and the UN by creating a very limited state.
It also recognizes the flood of prisoner immigrants dumped on them later in the book by the UN as a de-facto invasion, dumping immigrants on them faster than the population can absorb and assimilate them.
I also mentioned "Even Libertarianism, in its older, saner format before they went full leftist and anti-individualist" -
No, the ideology hasn't changed much - I'm referring more to the "adults" supposedly in charge, and specifically the statements of the current presidential candidate which are utterly antithetical to freedom of association, and are showing a disturbing trend that the leftist wing of the party is consolidating control.
Leftists talk a good game of freedom, until it's time to let someone else be free to succeed on their own terms, or speak against them, or oppose them, or fail because the leftists know what's better for you. And every organization that is not explicitly anti-leftist, will become converged.