The party would have dumped him, even though he had "clinched" the nomination by winning all those primaries. His delegates would have abandoned him, and voted for Clinton or Obama. The news that you cheated on your terminally ill wife coming out just days before you accept the party nomination.....that would be just too damaging, and the party would have pushed him out over it.
That would be an interesting "what if" timeline for someone to do. A blow-by-blow of the Dem. convention just as this news is coming out.
I agree but believe the democratic nominee would be hurt by this distraction from the economic message that McCain would have slipped in to victory in November. It would likely have resulted in a narrow Republican win regardless of whom the replacement nominee could have been.