Technically, Obama's campaign is probably correct if at least for the following reason:

If Hillary had lost the vote in Texas or Ohio, it was widely believed (Bill even conceded) she'd have to drop out.

She "won"* Texas on primary night, but only by a razor-thin margin. In all likelihood, that margin was the result of Rush's "operation chaos."

Once that happened, there was a good chance that she would stay in this all the way to the convention, except in the highly unlikely event that Obama won the remaing states by huge margins.

Therefore, Limbaugh's actions may be, in fact, what kept Obama from sealing the deal.

With that being said, given his strong victory in North Carolina and the close results in Indiana, it's hard to see any way that superdelegates would hand the nomination to Hillary. She may hang on for the next few weeks until the primary season officially wraps up, but with no big states left, how can she win over any superdelegates she hasn't already?

* The caucus results, however, meant that Obama actually received more delegates in that state.