Don't underestimate Hillary. She has come back before and she will again.I don't doubt that. But the base of her comebacks has always been working-class voters, hispanics, and women. In Virginia yesterday, Barack Obama beat her in all three demographics; and closed his margin in with them in the other two contests (Maryland and DC).
If her base is crumbling, then she will have a hard time launching any sort of comeback a month from now.
I'm not saying she can't do it, but the degree of difficulty climbs significantly with each Obama blowout.