For white people to be concerned with white genetic survival, the concept of the "white race" first had to be constructed. This is a recent concept, for eg. the Anglo-Saxons and the Celts are both "white" but the Anglo-Saxon English considered the [physically indistinguishable] Irish, Scots and Welsh to be a different, inferior race to them and used them to, as it were, "practice" the techniques of conquest, genocide and enslavement that they would later use on the non-white peoples of the world.
The point being that race is to at least some extent an artificial social construct, and I do believe it is possible for "white" people to identify as human beings above identifying as "white". I think this is rare, in the world we live in- but possible, yes. John Brown was ready willing and able to hack his "fellow" white people to death in his zeal to end slavery. Now even a man like John Brown had certain racist ideas still, which shows the extent to which even the most radical people are shaped by the societies they grow up in. But he was willing to put humanity above whiteness and to kill his so-called "own" on behalf of Black people, so I think it is possible for a white person to be pro-Black to some extent at least. Not likely, probable or prevalent, but possible. There are white people such as former political prisoners Linda Evans and Dr. Alan Berkman who I do feel have "earned their stripes" as true allies in the Black liberation struggle.