A Labour prime minister iof Britain in the sixties and early seventies, Harold Wilson, once observed that "a week in politics is a very long time." It has certainly has been a long time since South Carolina. So what comes next?
I believe it will not be decisive.  If Barack Obama wins 55% of the voters across the almost two dozen states goint to the polls on Tuesday or even 55% of the delegates, no one will assume that he has it sewed up.  Except maybe me.  But if Hillary wins with such margins, her campaign will try to steamroll the public back into the somnulescence of "inevitability," the trope with which whole Clinton effort began.
What with Pennsylvania and Ohio and Texas and other large states still to cast their ballots, this push to wrap it all up neatly and quickly will be an obvious spin. But it will just be a continuation of the Clinton attempt to keep Democratic democracy from having its say.
One of the problems with the missus is that she feels entitled to the presidency in a way that even George W. Bush did not. Of course, if she wins the nomination, and John McCain has the Republican designation, many Democrats will defect. Even many Democrats who are against the war.
First of all, the war is not the simple issue it was made out to be by pro-war and anti-war folks alike. Second of all, it is America that is in the balance for voters, not so much Iraq.  nd just contemplating the rancor which the aspirants to the throne provoke would make millions and millions of independents and Democrats turn to a sensible and honest person.  
Which, alas, Hillary Rodham Clinton is not.