That's the kind of sales job Obama will have to do with young voters, who've known him as president for the last four years. Maybe they'll decide he's better than the other guy might be, but the enthusiasm and excitement, the sense of endless possibility won't be there.
Bloomberg says their polling data shows young people, on college campuses and elsewhere, are much less motivated by the 2012 election. This does not bode well for Team Obama, which relied on motivated young voters in 2008.
I wouldn't predict young voters will vote for the GOP nominee. However they very well might stay home in large numbers, as they so often have done in the past.
It is one thing to believe a new man may make everything better, and quite another to believe that four additional years of the same guy is likely to be much better than his first four years. That requires a considerable leap of faith.