Not gonna happen. I expect they will still all be in come the convention (well, ok, not Hunter), and that no one wins on the first ballot - at least unless delegates start changing votes after the first count.
And then...they should rally around the nominee, Fred Dalton Thompson. Well, except for McCain or Huckaboob, because one of them will be the Demonrat VP npminee
My best case scenario is Fred/Mitt coming out of a brokered convention.