I was under the impression he was getting up there in years. I also think the reps will want to go with a "nice guy" . After the past 8 years of hate by the left, chances are the GOP will look for a squishy moderate to try to please everyone.
Cheney? He's 63. Another 12 years might be a stretch, but not unheard-of. Probably he's good for another 8; we can check again in 4.