Most of it falls into the category of, "See? We have Black people on our side too!" It's along the same lines of what they were hoping for with Palin in 2008 - they look at minorities and women so demeaningly that they're too stupid to vote the issues as long as the candidate matches their color/has the same sex organs. They actually thought Palin's having ovaries would pull women voters upset over Obama beating Hillary away from the democrats, no matter how stupid she was or Cro-Magnon her political stances.
If Carson did get the nomination, I think it would be likely that
1) a LOT of republicans in the south would stay home
2) he wouldn't do any better with Blacks than past GOP candidates
3) possibly a few percentage points of independents would swing to the GOP but not enough to matter
The only way Carson - or more likely Jindal since he's younger - becomes president is sometime in the 2020s if the GOP wins 2016 with one of them as the veep candidate, and assuming the GOP does win 2016, then barring anything happening to the president, that's 8 years before they can run for president because either the GOP wins re-election with one of them on the ticket, or they lose re-election after their first 4 years and are locked out for 4 years while the democrats are back in power. Maybe sometime in the 2020s, the GOP will be able to stomach a non-white candidate for president, but after 8 years of letting their racist bile rise as high as it has, it's going to be hard to tamp it back down in order to get their racist nutjob base behind Carson.
TlalocW