wow great thread!
its a great goal, but let me go a little hollywood on it and say that I don't think it will happen until some catastorphic event strips away everything that humans perceive as race. Not sure what, but something like the ever popular giant asteroid or a visit from aliens (vis. Star Trek).
Kinda like america has been slowly getting back together over the last few years after the two major events that stick out to me, 9-11 and Hurricane Katrina. Up to those points I can't really find a place in my mind that I remember the US acting as one country in the best interest of our fellow man.
And just because someone brought them up and I like a good counter argument. The Wizards Rules mentioned earlier are from a work of fiction by Terry Goodkind, but all of them make sense when viewed in terms of the world. The one I'd like to bring up is the fourth I believe: "The greatest harm can result from the best intentions."
Say we all begin to get along, slowly we forget hate and then eventually war passes out of memory. What then? Someone could use the old knowledge of war and completely take over the world with a little research and the human race would be powerless to stop it. (Kinda visualize Demolition Man for those of you who remember that movie)