The key is that the cascade of victories BEFORE OH and TX will convince the bulk of undecideds and soft Hillary supporters to support Obama in the interest of "ending this thing."  She would need to score a full-on knockout in both debates to stop him.

One of the problems with the analysis overall is the tendency to essentialize the Democratic electorate. We assume that all blacks will support Obama. Well, that wasn't true until very recently and might not necessarily stay that way. We assume that Latinos love Clinton because they voted for her overwhelmingly in California. But in Arizona they only gave 44% to her and in Illinois Obama dominated among them as strongly as he did every other group. Young people mostly prefer Obama, but young people voted Clinton in MA and CA. Older white women generally support Clinton, but not in Illinois or Idaho or Colorado. White working class union voters love Clinton...except not in Iowa. Every demographic can go any direction. None are set in stone. That's why telegraphing OH and TX based on numbers of blacks, Latinos or white workers is foolish this far out. If the race were tomorrow then, yes, the demographics would define it. But those big races will be after a cascade of Obama-friendly states.