Back in the days pre-20th Century race/ethnicity was considered greater of a deal and in fact contact with another tribe could indeed be legit harmful biologically due to the place in evolution genetics/disease was at. Since the 20th Century started and the urban revolution began in general, a whole lot of the new developments in technology like the automobile and other transportation mainly and phenomenon of outside ethnic restaurants or centers opening up in several places in many countries, the different groups intermingled more and more.
I'm not saying that is a good or bad thing necessarily, but I want to concede that the continued intermingling and assimilation could lead to the total loss of certain natural occurring traits like blond and red hair, which makes me sad I won't lie. Especially for the fate of the White European people, it definitely is not helping that over the last century there has been a movement that wants to deconstruct and lay excessive guilt on a whole people for what their older ancestors did before and de-breed them.
The point is that since food and weather/climate aren't just local anymore and anyone can move to another part of the globe, the concept of race and ethnic biology is no longer relevant, and I think that might be the inevitable path of technological combined with evolutionary progress. Once again, I'm not saying this is a good or bad thing, but it seems to be the way things are. I don't think race will ever be the same again, even if human civilization was "reset" to a pre-industrial state it would take centuries at least for distinct biological evolution and traits to revert if they don't just evolve into something completely different.