Remove the greatest difference among humans—race/color—and left are less obvious differences over which to clash, such as sub-racial identity (i.e. ethnicity), nationality, religion and so forth down that scale we tumble.
(Add a, say, contemporary deadly disease to the ugly equation and there’s a real potent fuel for the hateful fire.)
Therefore, what humankind may need to suffer in order to survive the long term—indeed, from ourselves!—is an even greater nemesis (perhaps a multi-tentacled ET?) than our own politics of difference, against which we could all unite, attack and defeat—all during which we’d be forced to work closely side-by-side together and witness just how humanly similar we are to each other ...
Before non-white people became the primary source of newcomers to North America, thick-accented Eastern Europeans were the main targets of mean-spirited Anglo bigotry.
Albeit no Stanley Milgram, I believe that if Canada were to hypothetically revert back to a primarily-white populace, if not some VDARE whites-only utopia, Eastern Europeans with a Slavic accent would inevitably again become the main target of the dominant Euro-Canadian ethnicity.