If Kerry did drop out,
1. would Edwards get the top spot? If so, his lack of experience would be highly questioned. He seeming incapability to deliver his own home state would also. And I don't see an Edwards (first term Senator, no previous elective office)-HClinton (first term Senator, no previous elective office) as a powerful union.
2. unless the polls have GWB at below 45% approval, I don't see Hillary trying for the top spot---too many questions on the campaign trail. Of course, for her Senate run, the media were complicit. Much of the media would be for her Presidential run, too.
Edwards-HClinton would be an experientially weak ticket.
No .. it would be who the delegates pick
Your points (in #343) are well-taken. I don't think Kerry will either drop out or be forced out over this unless there's very hard evidence document collusion. Good chance Berger did this for book material.