Here's a horrible thought, what if this did happen (God forbid) and Obama turned out as the "hero" because of it. Remember after 9/11 that George Bush's approval rating skyrocketed.
That's one scenario.
A more likely scenario is that Obama will be blamed for it, but that Obama and others would use it as an opportunity to seize a lot more power regardless and put into place a lot of government control over people's lives.