If Obama gets elected, I believe it will have precisely the opposite effect.
One, minorities will not get a free ride. When I was in the military, and few senior minority officers and noncoms were to be found, they were, if anything, harder on their own people than on the majority. I think this is a natural response of any fair man when given that responsibility. Of course, if Obama is a villain, this may not be the case, but then again, being a villain is not restricted to minorities, either.
Two, it is going to be very difficult for minorities to use their minority status as an excuse for their personal shortcomings if a black man, elected by white people (primarily) is President of the nation. I'm not saying minorities don't have obstacles, I'm just saying not all their failures are due to those obstacles.
Three, it is going to be very refreshing to see how Europeans and certain other foreign countries can continue their bashing the US as a racist nation when a black man is in the oval office, and not one European nation can boast one of their minority races, ethnicities, nationalities or religions is in a position of top national leadership.