F.C.
I will say that you need to talk to his wife and let her know that you are concerned and you think the time has come for him to retire. You need to also talk to him directly and be honest that you know he cares about his patients and can't imagine anyone taking better care of them than he does, but it is time that he find a replacement or another Dr to take over his practice. Let him know it is time he cared for himself and enjoy his life and retirement. It is hard for Dr's to give up what is so apart of their lives/self but if you are becoming his cruch and he is cancelling appts then he needs to retire. You can suggest that he find a younger Dr who would like to buy his practice but is willing to allow him to stay on as a consultant for a year or so. That may make the transition smoother.