I agree with your analysis. There’s little chance of any major shift in black voting patterns, but if they revert to their former levels of turnout at the polls, Obama is going to suffer significant damage. We’ll see the first real evidence of suppressed turnout in the 2010 mid-term elections (there may already have been an element of that in the NJ and Virginia governors races this year).
There was.
There was also the element of independent voters leaving him in droves.
When you realize who is wrecking the economy and it affects you, it also affects your voting.