"The best possible senario now is that Mongiardo establishes enough credibility to challenge Northup in 2006."
No, the best scenario is that Bunning wins 54%-45% and does not retire, Fletcher gets reelected in 2007, and Bunning retires right after the 2008 elections, with Northup being named by Fletcher as his replacement. She would then run as the incumbent in 2010 against whichever RAT wishes to run---probably not Mongiardo, who would be a has-been, or more like a never-was. Only problem is that Fletcher would probably prefer for Bunning not to retire early so that Fletcher himself can run for the Senate in 2010.
If he's going to "retire", which I think is a rumor too many of us are coming up with based on Democrat talking points and propaganda....but anyway, under that scenario he should do so before the 2008 elections so that his replacement and McConnell are running concurrently. That would strengthen the ticket.