The best possible thing would be for McCain to find an great conservative black as VP. And then have Hillary somehow steal the nomination from Nobama.
This may actually be an opportunity for the Republicans. Think of it, the African-American demographic is actually very strongly conservative on social issues, and most vote Democrat primarily out of tradition (and the shrill urgings of 'black leaders' like Sharpton, who are slowly losing their level of influence). This could be a major inflection point that is similar to that which shunted Blacks from the Republican to the Democrat party (simply because it seemed that the Democrats were more for Civil rights than Republicans, which at the time I'd say seemed the case. This made Blacks move from the party that had actually stood up for freeing slaves, even though Lincoln may have had other subtler reasons for doing so it is still the Republican party that stood for this, to a party that had been the fount of the White supremacist movement in the South ...the Democrat party).
Imagine what would happen if Obama, who for lack of a better word is revered by blacks and young voters, had the nomination (for lack of a better word) 'taken away' from him.
That would be the death knell of the Democrat party, and Hillary would just have won herself a Phyrric victory (sp). I think this is a great opportunity for us, especially among young upward mobile blacks (college degree, professional background), and middle-aged black professionals (who would be typical Republican voters ....were it not for the fact that they vote Democrat).