Look, Barack Obama is not going to get the Democratic nomination. Hillary Clinton is. Polls, delegates, and so on don't matter: she has it in her sights and will obtain it. Now, she may get crushed by McCain in the general election (although possibly not), but she will have it. She'll destroy what's left of Bill Clinton's "legacy" among Democrats, and Obama will be consigned to the Senate for the rest of his career (although I think he'll eventually go back to academics).
I think the Democratic Party will ultimately be glad they didn't run him, too.
As TS O'Rama notes in the comments, mine is a pretty darn bold prediction, and so I feel as though I should give a better account of my reasoning.
The way it seems to me, it's just a function of how much Hillary Clinton wants the nomination in relation to all other factors. This is her raison d'etre. I can't say it was the case from the beginning, but certainly by 1992 her marriage with Bill was largely, and perhaps completely, one of mutual political benefit: she acts as the proper wife-prop for a President, and in return he uses his charisma and capital with the Democrats to get her to high office (and allowing her to pursue policy while he's in office; her quote "I want domestic" in exchange for not divorcing Bill for his affair with Gennifer Flowers). She was essentially given a Senate seat and it was known that she'd eventually have her turn to run for the Presidency with the Democratic nomination. I strongly suspect that the reason Hillary threw an ashtray at Bill (the sitting President of the United States!) upon learning of Monica Lewinsky wasn't for his unfaithfulness but for damaging his image and her future chances.
However, in the primaries another not-while-male candidate who had been gifted a Senate seat and was being groomed for greater things showed dazzling charisma and his message of "hope and change" resonated more powerfully with the Democratic base (if not necessarily centrists and political independents). I also strongly suspect that for Barack Obama 2008 was meant to be a warm-up, either to be Clinton's Vice-President or to run in 2012 or 2016 once he had some more US Senate experience under his belt (as his political resume is pretty thin). Edwards was the socialist from the losing 2004 ticket, and was never a serious threat. Nor was Bill Richardson, who while being a governor and being hispanic, wasn't very exciting (not to mention how hard it must be to gain traction as the "First Hispanic President" with a last name like his). Obama had an exotic name, a great stage presence (his voice is different now...early in the campaign it sounds like he was trying to imitate David Palmer), and was a fresh new face.
This leaves the Democrats with a problem: Clinton was supposed to be the nominee. The skeletons are (presumably) out of her closet and she's a seasoned politician (and a woman!). Whichever old white guy the Republicans put up, especially in the wake of two relatively unpopular Bush administrations, presumably would get creamed. This election was theirs for the taking. However, Obama's sudden and unexpected ascendancy screwed up the timeframe. Instead of a potential sixteen years of uninterrupted Democratic Party control over the Executive Branch, they risk another four or even eight years of the GOP.
Hillary Clinton has sacrificed everything for this chance. I can't see how she could be bought off: she's not fit for the Supreme Court (not to mention that the Chief Justice is relatively young) and Senate Majority Leader isn't much of a prize. If she doesn't get the nomination, all the years of the cheating husband, the knowing smirks, the pretenses require politics will have been for, in the end, nothing. MAYBE she could run in 2012...but only if Obama loses in the general election. This is her chance, and if it means clawing her way over Obama's political corpse then so be it: the Democratic party obviously isn't going to simply sit out the election; it'll be forced to rally behind her. Besides, she's the wife of the "Comeback Kid" and in her mind she's just as capable (and probably more) than he is.
Bill Clinton also can't afford for her not to get the nomination: he's also staked everything on it. Before, he was the beloved elder statesman of his party, with the base pining for the years of his administration. Now...he's lost that. He's somewhat despised, and for a man reportedly concerned so much about his legacy that's clearly unacceptable.
To the Clintons, there is no tomorrow. The upstart Obama must be crushed...either he'll agree to run as VP or he'll be brought down in a hail of scandals and suspect political affiliations.
Some have mentioned Al Gore as a potential "compromise" candidate, but what this ignores is how polarized the primary has become: it's seen as the historic race where either a woman or a minority will finally break the long streak of white men. Al Gore is...a white man. His nomination would be seen as a betrayal by both Clinton and especially Obama loyalists, who may simply sit out the general election or vote for a third-party candidate.
The Democrats know what they face: a centrist Republican war hero with (presumably) no skeletons in his closet. He still fairly spry, but he's old: it's conceivable that his VP could take over due to future illness or death of McCain and maybe even be elected in his own right once...or even twice. Obama, assuming he's not a charred corpse by June, isn't going to win enough of the center. Gore would lose some of the base, even if he did pick up some of the middle. Clinton, for all her faults, is seen as at least sorta-kinda on a similar footing with McCain: centrist-ish Senators with years of political experience. Running Clinton is the "safe" option: she has a shot at winning, and even a loss wouldn't be too terrible: the Dems could take credit for running the first female candidate for president. Having finally exorcised her from their future, they would probably still have Obama as a viable candidate (and this time with experience) next time.
Clinton is the safest bet for the Democrats and the one by whom they'll lose least in terms of political capital.