In order for that to occur, we'd first need to encounter a non-Earthly threat so that they could become "the others" and Earthlings could band together against them. Unless we are presented with a large threat that forces us to band together and overcome all the smaller divisions, then the smaller divisions will define us. Example: Britain and France were rivals for a long time, but eventually they had to overcome their division so they could group up against the external threat of Germans. That rivalry continued for a bit, but eventually Western Europe had to band together to counter the threat from Arabs. And so it continues, with each tier of rivalry being solved when a new, broader threat is introduced.
The Dunbar number (
https://en.wikipedia.org/wiki/Dunbar%27s_number ) gives us a baseline for divisions to begin. We will always treat people we know differently than people we don't know. It's just a limit of our biology. To avoid this trap, we'd need to give the reins of the society over to non-humans. This could mean genetically engineering our descendants into a form that is not human. It could mean allowing ourselves to be taken over by superior AI.