The only problem I'd have with Cal leaving right now is that there aren't really any true proven great coaches out there. You have your legends (Cal, Roy, K, Self, Pitino, etc) but they're not realistic. Few is going nowhere. If Cal ever left, you'd have to throw the bank at Stevens or God forbid, Billy D again.
There are plenty of really good up and comers, but do you take a chance on one of them? Sure there is a chance that an Oats, Beard, Mike White, or hell even Mark Pope could kill it here. There is also a chance that they'd get swallowed whole and completely **** the bed. "Kentucky isn't for everyone" doesn't just apply to recruits.