That's the people, not the culture. The Goths, for instance, adopted the culture of the Romans. Anglo-American culture is an adept, adaptable culture. It's not perfect by any means, but it has probably more positive traits than any other currently around. The major problem, in fact, is racism and particularly the black-white schism.
Whites who fear falling out of majority position fear "what goes around, comes around," but that need not happen if those who merely fear the loss of a white America would loosen their grip on that concept.
But by 2045, the vast majority of Boomers--the last generation into which racial segregation was inculcated--are dead, that fear will have largely dissipated.