Ethnic and racial divisions are largely the result of populations being isolated throughout humanity's past. The differences of geography caused the differences of skin pigmentation generated by the differences of solar radiation exposure from the specific locations human populations settled. Other superficial physical features are based off of a similar evolutionary adaptations based off of location. As biological sciences, especially genetics, has exposed and shown that humanity is genetically identical with only superficial differences in appearance. As an unfortunate repercussion of anti-science and deliberate attempts to keep populations illiterate to scientific truths, the delusions of racial superiority continue to exist and inflict harm upon the world.
If we consider the notion of what racial supremacy is based off, it is of an illusory delusion. I say illusory delusion because the illusion is that of superficial physical appearances and the delusion is believing an isolated population is capable of being "pure", genetically speaking. The notion that any specific population of humans for whatever myth they claim to justify isolation, fundamentally is ignoring the genetic reality that no population in any ecosystem within the greater biosphere is capable of being completely isolated to the point of genetic "purity". Any conception of "purity" of any race or ethnic group of people for any reason is a complete mythology of those people's history. Science affirms the reality of a genetic heritage amongst all of humanity, and all of life in its entirety. An ideology that typically coincides with theories of racial superiority is the equally illusory delusion of anthropocentrism. Anthropocentrism is the ideology that humanity is an apex species and therefore existence must bend to the will of humans for the benefits of only humans, and that intelligence only exists within the human species and that all other lifeforms are lesser. It is an ideology that has justified the commodification/exploitation, breakdown and near collapse of the biosphere, and the enslavement of entire species which witness the slaughter of hundreds of billions yearly purely for the sake of consuming and discarding.
If we consider the cause of the superficial divisions of race and ethnicity is of populations forming and maturing in different geological locations that result in a quasi-form of isolation. Then the logical solution would be an increase biological replication to intertwine and blend genetic variations, i.e. sexual relations.
This is honestly the inevitable solution to the problem of racial and ethnic purity in any culture. And if we were to establish transportation and communication systems interconnecting every city, town, and settlement the level of ability for human migration would be exponential. And in an automated economy, travel and a work free environment would allow for far more time for things like the sciences, arts, and biological aspects such as hedonistic pleasures/reproductive acts. If we factor all of this into account, the ability of migration for human populations across the world would eventually intermix pigmentation and other superficial features. Especially since the isolation that developed specified pigmentations would not exist in the same manner due to a constant migrating human population.
The intermixing of human populations, extrapolated exponentially once human populations are freed from drudgery by an automated economy and free access of movement; could result in an evolutionary jump of the human species never seen in human history. The coagulation of human culture into one coherent multi spectrum non-hegemonic globally interconnected system facilitated through technological means such as the Internet and physical means such as highly advanced transportation mechanisms. Would be able to stimulate an economy and civilization that could expand exponentially into the greater universe. Not only would the increased copulation dissolve the illusion of racial and ethnic divisions; but it would also exponentially grow the human species in numbers. A common myth is that of overpopulation, the claim that it is the number of humans that is resulting in the destruction of civilization and the biosphere. Rather than the habits and behaviors of the existing human populations that are wasting the resources and massively mismanaging them.
An increasing level of human population with an interconnected global culture and civilization that is automated for abundance and frees humanity from drudgery would have the logistical means to assert a claim of a unified human species. It would not be a dream of utopian fantasy, human biology is estimated to eventually evolve equalizing pigmentation and other superficial features eventually given enough biological evolutionary time. But we as wise apes (Homo sapiens) are capable of self evolution. Interconnecting the human populations across the world into a single global coagulation of culture and civilization is an evolutionary inevitability. The delusions of separation driven by and paradoxically driving the ideas of racial supremacy are attempting to fight biological truths and laws, their philosophical disillusionment will eventually collapse on itself and its contradictions.
Let us look forward to what the logical and rational outcome of human evolution and civilization advancement if we simply conceive the ideas of connecting with one another on a communal, global, and personally intimate level. The repercussions of simple subjective intimacy among the greater population and the desire to migrate throughout one's life are the basic ideas that would be required to generate the inevitable future described. The true repercussions of the fullest extent sexual intimacy has upon a globally connected society has yet to be fully seen.