Of course it could win an Oscar for Best Picture. It made potloads of money, it's politically correct (crazy terrorist for villain and ruthless martyr for hero,) and the Academy is infamous for lapses in taste and common sense.
And given the popularity of the wacky auteur theory, Nolan is thereby a possible.
And Ledger would even be a plausible choice for Best Supporting Actor, except he's actually the star of the movie. But such piddling details never bothered the Academy before.