From the first time I started seeing Obama as a serious candidate in this election, it was obvious to me that he could not win if the same old people voted. But it was also clear that he was better at attracting people who hadn't voted before to the political process -- better than any candidate in my experience. In fact, that's why he's gotten as far as he has.
The way things are looking today, Obama is on his way to a narrow but definite defeat among the people who would have been expected to vote two years ago. He won the primary based on bringing new people into the political process, but even those new people aren't enough to carry the election. But if he can do what he did best in the primaries again on a general election scale, he can win, and win big.
The outcome of this election hangs entirely on how well Obama does in reaching the apathetic majority.