Hoppe walks through the issue of who owns the property.  In an ancap environment, it is clear: all property is owned by individuals or private entities.  In such an environment, it seems difficult to disagree with Hoppe's conclusions on immigration.

He then moves on to some version of monarchy and ends with a look at today's western democracies.  Here is where the issue gets cloudy for some.  They are unwilling, or unable, to extend the principle that is perfectly sound in a completely private-property society and apply it to today's world.

I have two thoughts on this matter:

First of all, the discussion gets so cloudy because the state is right in the middle of this. Given we have a state, I suggest the only legitimate functions of a state are to secure the property and life of those under its jurisdiction – call it a mutual aid society for enactment and enforcement of the NAP.