Absolutely, as long as anti-hillary forces rally around a candidate in time. If Obama runs, he'll win the nomination. If not Obama, Edwards will have to quickly push out all the other candidates, and claim the mantle for himself
Is it really necessary for the anti-Hillary forces to rally around one candidate in order for her to lose? That's not what happened in 2004, when Howard Dean's candidacy collapsed. In that case, he was being attacked from all sides by multiple challengers, and the combination of those attacks with his own foot-in-mooth disease ended up causing his candidacy to implode. It was never really a 2-man race. In fact, up until about two weeks before the IA caucus, *Gephardt* was seen as his principal rival in Iowa.