Herman could vault to the front with a few key endorsements. i.e. if Newt, Santorum, Bachman and Johnson withdrew and threw their support behind Cain.
It could happen. It should happen;)
If she's not going to run, a Palin endorsement might work wonders for Herman Cain, my number one choice if she's not running.
My fear is that all those you mentioned plus Palin will be in the race, allowing the most liberal Romney to sashay away with the nomination, with the help of democrats in open primary states such as my own.