I am in complete agreement with this thought, and the good thing is, it's already happening. Why? One world: globalization. Because of this, the practical implications of a 'nation' is becoming blurred, and the world is instead being sorted by ideology - democracy, communism, Islam etc. Fortunately democracy and freedom is winning. Decades ago there were over 2 dozen communist countries, but now there is only 2 true communist states. The rest, eg China, Japan, South Korea is being diluted by western ideology. SKorea and Japan are already a democracy.
So to look at the big picture, we all came from Africa but have branched out into the world as the human race progressed. We aren't going back to Africa. I mean look at Europe, they are a good model.. many countries have become part of European Union and they use the Euro currency. Soon Russia and America will also be working more closely with Europe- France, Germany, UK etc.
The World is our Oyster and and no leader or government have the power to control where people choose to go. To see peace through we ought to view the world as a whole and not be constrained by artificial boundaries.