There is virtually no mathematical way that Hillary Clinton can win the nomination. Take a look for your self at Slate's Delegate calculator. Move the sliders around to give either candidate a percentage of the vote and it will estimate the number of delegates they will fetch. If Hillary wins every single remaining contest, she still is about 100 delegates short. Of course, she will not win every remaining contest unless someone unearths bodies from Obama's back yard (or even better - his lobbyist connected, NAFTA funded, recently sold adjoining property that is now a neo-black panthers headquarters). So this means she needs the super delegates to break overwhelmingly for her, and right now her lead in pledged super's is down to 30 from over 120 early on. So, why is she vowing to fight on until the convention in August?
Because she believes down to her core that Obama can't win in the general election. So the only way to save the party, is to destroy Obama and take charge of the situation her self. This is an inherently loosing position, one that Mike Ciresi's senate campaign tried to no avail in his contest against Al Fraken here in Minnesota. The general argument is, 'There is no way people will vote for him because he is ________ , so vote for me." Combined with, "You know the Republican war machine will destroy him because of _______. They can't touch me though."
To me, it is a weak and fearful path to take. Any Democrat can lose, just like any Republican can lose. Or win. Every one got behind John Kerry because he was a war hero, and so was "more electable." But he lost because his opponents turned his strength against him, made him into a flip-flopper, and it was over. Its not about what you are, its about how you play it.
I do predict that by the 4th of July Hillary will be out of the race. Her stating that she will be in it until August is just to show her total commitment to the process and her expectation that Obama will live up to her low expectations. But ultimately she just can't do it, will run out of money, and be forced to withdraw. Unless they find the bodies.