If, by some chance, Hillary pulls this thing off, what do we owe her?  And why?

The argument goes that no matter who wins the nomination, Democrats should rally around the winner because it is better to have a Democrat in office than a Republican to preserve our Democratic ideals.  United we stand, and all that.  Right?
I agreed with that six months ago.
But, after lagging behind for months now, has she earned that begrudging support?  Has she been a gracious underdog?  Not exactly.  She is facing a movement, and all she can manage to do is try to stop it in its tracks.  I can understand that, having been the frontrunner for so long, the Presidency is a hard thing to let go.  But this movement could be one of the best things to happen to the Democratic party in a long, long time.  Her campaign is now acting in the interest of Bill and Hillary Clinton, not the Democratic Party.  Her campaign is aiming to drag Obama to the ground, and make him so "unelectable" that super-delegates have no choice but to nominate her.  
She wants to be the nominee by default.
Even as a big fan of the Clinton administration (I stood in line for nine hours to get "My Life" autographed), I believe that a Clinton-II would be as philosophically wrong as Bush-II.  We are willingly creating an infant oligarchy.  We can see it in the way Hillary is clinging to the nomination as if it is her birthright as a Clinton.  We'll no doubt see it again when Jeb Bush runs for President.  Hillary believes the nomination, nay, the presidency, is hers, and she has already shown the willingness (supporters call it her tenacity) to drive the party off a cliff in order to claim it.  
Party unity?  You first, Hillary.
But why am I so morally ambidextrous that, if Hillary is the nominee, I can abandon my core Democratic values and vote for John McCain this November?  There are several reasons, owing to the fact that principles are more than party-deep.
First, blind party-loyalty is wrong-headed.  Saying we Democrats can't be progressive and principled, and vote for John McCain over Hillary, makes no sense at all.  How can I, as a principled Democrat, vote for the candidate who said Barack Obama isn't a Muslim "as far as she knows," over the candidate that has been pressuring North Carolina Republicans not to use Pastor Wright as an issue?
Second, I believe you have to earn the presidency.  And there is no cookie-cutter definition, no "commander-in-chief threshold" for having earned that office.  It can be as grueling as being a career military officer who spent five years as a POW, or as "simple" as inspiring the nation to do something better with itself.  Spending eight years as first lady, then feeling entitled to give it the old college try, doesn't cut it.
If the candidate that inspires is knocked off by the candidate of entitlement, a principled Democrat can, in good conscience, vote for the Republican.  If Hillary is so unwilling to heed process, and rules, and "voting," she has not met the commander-in-chief threshold.  
She can tear the party apart for her own sake, and claim that, hey, that's politics.  But I can vote for someone else, because hey, that's Clintonian party unity.