My guess is that Rock won't flip unless there was a massive hole to fill..and I mean massive. 104.5 flipping would leave X open to attack from Clear Channel....now that the Market Manager who hated Planet left, could very well relaunch a version of Planet on 97.9 (if that Now thing doesn't do more than Kiss did). I still maintain that a Modern AC, not Hot AC, but MODERN ac on 97.9 makes a ton of sense between APE and X....but what do I know
If Cox were to flip FYV, the choices are limited because certain formats are taken or would hurt someone in the cluster. I'd vote mainstream AC and attack EJZ (similar to Magic in Tampa)...it's the most mass appeal on a giant signal.
That being said...let's not kill off any more rock stations, even if they don't play currents (hint...one or two current/recurrent tracks an hour wouldn't kill X - last time I checked, X isn't playing a lot of Mudvayne, Five Finger Death Punch, Avenged Sevenfold)