So long as people do not infringe upon other peoples rights to the property they own, a truly free humanity ultimately has to allow all the worlds people the freedom to live and work wherever they so choose.
If people are wanting to migrate it is because they seek 'advantage' and often that advantage is state welfare (tax-payer money taken by use of force and redistributed without approval), often it is that migrants will work for lower wages than the state imposed legal minimum dictates, often it is to escape the failings of the state from which they come.
A world without states would not have guards, fences and prisons for people who were born in one place just defined by lines on a map and controlled by people who simply pronounce it is they who are in control and so only they can wear the special hats!
And before too long the economy would settle, by a simple process of natural attrition, like a woodland can manage itself, a river workout the way to the sea, a bird learn to fly on the windiest of days.
The natural world does not need organising, by people in special hats, it can look-after itself and, when allowed to do so, quickly finds the optimum manner and with beautifully efficiency but yet breathtaking complexity too.
I am not saying we have to 'return to nature' or such - we must continue to advance. I am saying that we need to rediscover how to only allow all human macro-systems to dictate - roots-up - the structures of our global society.
We need the confidence to shrug-off the burden of our belief in omnipotent rulers being necessary, a paradigm remaining that is nothing but an ugly vestige of the past.
Sure it would be difficult to just open the world's boarders 'snap'!" - but we will have to rapidly evolve to this nirvana because, no matter how many rules and systems we impose, the concept of the state is failing. The state will eventually, can only but, fall as dust through our fingers no matter how much we think we have no better option or want to believe.