Bowie's never shared his name on record before, I don't think he's going to start now. I think the most likely would be an Iggy project. Something in the vein of 'Avenue B' could really work well.
I think it's about as likely as McCain being assassinated before Obama personally, but, I would cream my pants if it eventuated.
I used to be with it, but then they changed what "it" was. Now, what I'm with isn't it, and what's "it" seems weird and scary to me.