that would be nice but the last 60 years have proven that doesn't work

The fact that it is not what happened does not mean that it "doesn't work". Far be it from me to pretend to know what can happen or what will happen, but I don't think you know either.

liberalism has no defense against it

Maybe the failure is liberalism's and not that of the idea that people should be treated as people regardless of race, which originates not with liberalism but with Christianity, and possibly before.