Let's think for a second.
Would such a world benefit mankind? Would it destabilize the current geo-economics? Is there even a remote possibility that we as humans let go of this ancient tradition of drawing lines on sand that have only served to create problems among masses and has done NOTHING good so far?
will you allow other people to sleep/eat/live in your own house ? i think not.
you see the human nature is designed or could be "programmed" to live within borders, they start small at your own bedroom that is surrounded with borders , then goes to your house as a whole building, then a yard if you have one , a street , a city/state then a country.
how can we convince the rich countries to share their resources with the poor countries when we can't convince our own kids to share the same room?
it is a beautiful dream that i would love to see , but sorry to tell you , this is never going to happen on any large scale
You are mixing privacy with nationality. You take pride on the borders drawn by others, accomplishments achieved by others and take credit for it. That is the biggest reason nationalism sucks.
But privacy is individual. Your doors do not equate to the border of your country.