I would expect that the R party will split along its internal division, with one half retaining the name and stealing a significant whack of people from the D party, while the other party will swith to D or to a third position, though those tend to be only temporary in our system.
Interesting thought, Shag. I believe we have seen some of this already. Take for instance Giuliani and McCain. I feel they are a bit.... misplaced?