IMO its the opposite. I read somewhere Independants are breaking for Mccain at higher clip then Obama, but Mccain needs to be winning by 1-2% if he is going to win that state/overall election.
1. Younger vote. We often hear this, but polls don't take into consideration people with only cellphones. Certaintly people with no landlines/younger people will BREAK for Obama heavy. In addition alot of younger voters aren't included in these polls because its often "likely" voters that are polled. This year they'll be record turnout, so this favors Obama.
1b. Alot of states have same day registration. This will favor Obama as alot of new voters will be breaking for Obama.
2. Obama ground game is MUCH better then Mccain. Traditionally this is where the dems lose. But this year they will be getting out the vote like never before. I read somewhere this alone will be giving Obama 1-2% in votes.
3. Mccain will lose votes to Barr in key western states/florida. There are certain republicans, although very small, that certaintly won't vote for Dems, but aren't swayed by the christian wing of the reps. As illustrated by support of Ron Paul, who endorsed Barr I believe. Current polling doesn't show 3rd party votes.
The thing about the key words in your post "younger" and "voter" is that they don't go too well together.
They are younger and so they likely won't vote.
Apathy!