Racists are impossible to change. It's because they are taught at an early age to hate, either by their parents or siblings. Racism is taught, it's not something I think most people have until they are pointed in that direction. For example, a racist father teaching his children hate. If these kids were never taught to hate someone in such a way, I bet we'd have less and less racists around. But sadly, we still live in a world that still pushes these beliefs on their kids, so they too become racist bigots.
Racism as much as I hate it, isn't going anywhere. There will always be people with some racist tendencies. It comes down to teaching the young before it's too late.