A lot of things can happen between now and the end of the convention, but the suggested scenario seems very unlikely...
And no, I would not favor Hillary's candidacy over Kerry's. Her persona is the only one in American politics that even approaches the divisiveness of the Bush Persona, and the need to oust GWB from the oval office outweighs all other considerations.
I'm only interested in fielding a candidate who can win, and, like it or not, Hillary isn't that candidate...
Kerry's mostly lying low at the moment, letting everybody else do most of the talking. He's been known to be very strong in the homestretch, however. And that's where it counts, at the finish line.