I don't think this is true any more. I think there are as many people who would love to see a minority or woman president as there may be some old-timers who shudder. Pop culture worships the minority of all kinds these days. Why else would "Will and Grace" have been so popular?
I think you're right about that. With the right candidate I honestly don't think that blackness or femaleness is the automatic hindrance it once was. Sure there are a few for whom it will matter, but few enough I think that they'll be cancelled out by the few that vote *because* of that trait.
In Obama's case, it's not the blackness of his skin that will be the problem, it would be the blackness of his talking points. The same tired old class envy victimology just doesn't get the mileage it used to. Thank God for that.