They could never enact a genocide these days. They'd love to, but they can't. Everyone in the first world is holding a camera at all times and has access to a global internet they can upload pictures and video to in an instant. Genocides rely on denial and coverups to work. That's not possible any more, not to the degree necessary. Even with social media cooperating to the fullest, you can't stop every single piece of evidence.

They'll still work on a soft genocide via replacement, invasion, and oppression, but it has to be slow enough that the world at large has plausible deniability in saying they didn't know what's going on, much like what China is doing to any non-Chinese person living there.

There won't be a night of long knives or a holodomor. There will just be fewer white people and uncooperative minorities every generation for the next couple centuries until they exist as small, scattered tribes with no relevance on the world stage, much like any given indigenous population.