And "in the future" - what does the future look like? Should we race-mix with asians to boost our IQ as humanity slowly transitions to big-brained, physically weak alien-like creatures - or should we mix with blacks and get lower IQ but more testosterone/muscle mass to survive the mad max apocalypse?

You said it yourself natural selection helped us keep the superior genes (more useful for our environment) we have today from Neanderthal contributions EPAS1, HYAL2, and STAT2 while getting rid of the ones that weren't as useful. In this scenario, if individuals had contributions from all 3 of those races mentioned then natural selection as was demonstrated already will mean we keep the best going forward. It isn't mutually exclusive between hapa or mulatto. From a moral standpoint, people should have the freedom to procreate with who they choose but the narrative that this will certainly result in a degenerate future people is a lie.

There's nothing Europeans need that we don't already have.

The obvious is Europeans could also be the top sprinters, improved immune systems, with higher IQ's and going forward with the best traits: just as the human race already has and will do. This shouldn't be forced though, obviously, there should still be other variants such as how Neanderthals shouldn't have gone extinct and could co-exist with modern humans.