If you want to understand how Nazi Germany managed to convince the german population that discrimination and ethnic cleansing (not even genocide, only forced removal) of ethnic/racial minorities was socially acceptable you just have to read the OP and observe 21th century America in general.
You have 320 million multiracialist zombies openly, shamelessly advocating, celebrating and sometimes even mocking the genocide of an entire racial group.
You can't make this shit up.
I don't want more useless poor people from south of our border in the United States. I just accept that because of ease of travel and fusion of cultures humanity will eventually homogenize its skin color. I don't see it as scary or bad, just as an inevitability. White won't be the only skin color that disappears. If you use your brain and listen to what scientists are saying about it you'll see that it's really not something that can be avoided, not permanently anyway.
Your culture and your descendants are not at risk. They'll just be a bit different than you, as it has always been, and there's nothing wrong with that. Fighting change is an exercise in futility.
What if, in 50 years, we are able to engineer the racial attributes of ourselves and/or our children?
I suppose that's possible. I think something like that might extend the timeline somewhat, but ultimately the result will be the same in my opinion.
Do you think that we will ever move to into space? Or was the Apollo program a silly one off?
Will we put a colony on Mars eventually? I see that as likely. Will we put humans on a planet orbiting another star? I don't know. I like to think it's possible. Underestimating humanity is usually a losing game.
Spreading across planetary distances, or more, that impacts the idea of genetic fusion.
Has that been taken into account in your prediction?