Even if there were no "white colored" people on Earth anymore, many people who are nowadays considered "darker skinned" have Caucasian ancestors, meaning white people cannot go extinct unless all the other so called races also go extinct too.
Reminds me of a scene from Days of Future Past, where Bolivar Trask talks about how the humans supplanted Neanderthals, and being an OCD trivia nerd, I wanted to shout at the screen that modern humans
are Neanderthals, sorta. Many of us have Neanderthal DNA, meaning their line never really died out.