This article talks about how all hints of racism disappear when people are assigned to a group together. This shows that the real problem is tribalism, and that racism is a small subset of that problem, one that can be eliminated fairly easily.
People are naturally hostile to anyone that they perceive as being foreign. But one of the best things about the modern world is that our concept if 'non-foreign' has expanded dramatically. In the ancient past, anyone outside your tribe of about 150 people was considered worthless, and you could do anything to them without any moral penalties from the group.
There are still places in the world where people think like this. But the remarkable thing about modern, developed countries is that even the most backward racist bigots will consider a vast number of people to be non-foreign. The impulse to consider outsiders less than human has been confined to others who have some obvious physical difference, with everyone of the same race being a non-foreigner by default.
Of course, the tribalism instinct is so pervasive that it often finds new outlets, even if people are trained to ignore color. Political affiliation and ideology often activate tribalism, with those who think differently automatically being seen as less than human.
We have made great progress in weakening the tribalism instinct. But we will never eliminate it completely unless we continue to attack it directly. Focusing on only one manifestation will simply cause the problem to mutate and reappear in some other form.