I think whenever white pols start preaching self-reliance to black audiences, they are largely tuned out without consideration. Cain would be different. Here is a black man who made it to the top of the corporate world without relying on government to get him there. He would still get a decided minority of the black vote, but he would probably get enough (20%) to make a difference.
Rainbow Push Coalition knew him and supported him. He is probably as well known as Obama was among blacks