I freely admit that I don't know what the Senate will do. NOBODY predicted ahead of time that the Gang of 14 would pull the rug out from under us.
IMHO it boils down to what Specter does. He killed the Bork nomination and saved Thomas. He has always been the key swing vote on the Judiciary Committee; as Chairman he carries even more weight. I just don't see him supporting JRB, but at this point there is not too much to lose by nominating her or an equivalent and rolling the guns up to the top of the ridge.