For Christmas, my son (age 4) received an abundance of gifts, including knights in a plastic castle, Rescue Bots (i.e. Transformers for the younger set), and Dinotrux (which are pretty much what they sound like).
They were not allowed to interact with each other.
Okay, not that last one. But still.
Whenever he wasn't looking, I'd place figures into a different playset. When he found them, he'd get angry and knock them to the floor. His older cousins would try to play with two types at once. Characters would be smacked aside.
"No mixing allowed!"
And then, on the fifth day, a miracle. I locked the Dinotrux's food — a piece of ore — in the castle. I suggested the Dinotrux and Dinobots should band together to get the ore back. And he said... "Yeah!"
They worked together and recaptured their ore. Then I sat back as they all sailed the Rescue Bots' ship to his cousin's Hot Wheels garage for a party.
See, America? If you make desegregation fun, people will embrace it. All you need is a little perseverance, and bigots will go the way of the dinosaur.
Which, based on toddler toy industry, means they'll become either half-robot or half-truck. That should be more than enough incentive for them to give up their racist, hateful ways. Right?
If not, we'll just have to throw in a giant Hot Wheels dance party.