You really have to wonder how this country would be different if MLK was not assassinated. The group that took his place was not driven by the Civil Right cause, but their own self-promotion.
Like all race-baiters, MLK would have set the goal posts further out, and he would become what Jesse Jackson is. I think people here are giving him too much credit. If the centrality of his message was “Yes, we’re put-upon, but let’s build a moral society amongst ourselves and prove we’re better than they think”, then, yes, MLK would still have had a positive effect. But everything he did was aimed at the government and without moral leadership, we have the black society of Trayvon Martin.