I really don't know what Europe is going to do over the next century. These countries are homogenous in a way that's difficult for Americans to comprehend. Forget "white" versus "brown"--Germany is 86% ethnic German. It's one specific tribe of white people with a flag. It's been almost half a century since Germany began a family reunification program for Turkish immigrants, and the Turkish population still hasn't assimilated, much less reached parity with native Germans. (Meanwhile, in the same amount of time, multiple refugee groups, such as Cubans and Vietnamese, have achieved economic parity with whites in America.)
I love Germany and Germans. My wife is a fluent German speaker and lived there. We have had several German au pairs who are now family friends. I have family in Frankfurt who immigrated there from Bangladesh, and they seem to be doing okay. But personally I would never immigrate there.