It’s good that you’re aware coaches can move. As others have said, it happens all the time. I doubt any coach is going to hint at a desire to leave, so I don’t know if you learn much by asking. You can look for indicators (established in area, spouse working in the area, kids in school) but ultimately those things are just a bit of friction if a great offer comes along. You’re probably better off looking at how the AD has filled jobs in the past and if you see red flags there. Generally I view the coach as a potential disqualifier for any given school (if you hate the coach, drop the school from the list), or perhaps a tie-breaker between schools a recruit would equally love to attend. But it’s pretty risky to choose a school for the coach alone.