It's not far out imagining that the expanding reach of the size of our "tribes" or herds could encompass all of humanity without prejudice or discrimination.
Nice dream but its Never gonna happen. For starters followers of several of the worlds religions are never going to submit to being equal with anyone else and that means billions of people not playing along right there.
As for illegal and uncontrolled/unregulated migration forcing the issue, well, yes migration is going to increase but so to will the backlash against it. Interesting times ahead. All I can say is I am glad I am in NZ~!
For me the bottom line is humans are tribal by nature and I don't see it changing any time soon.