The hullabaloo 50 years ago about interracial marriage followed a very similar course to what's happening today: http://en.wikipedia.org/wiki/Loving_v._Virginia

For a long time, everybody was opposed, but now it's just fine with most people:

http://www.gallup.com/poll/163697/approve-marriage-blacks-wh...

Hardcore racists now know that talking about "miscegenation" will get them ostracized. So yeah, the KKK is a pretty reasonable parallel here.