1. Faculty member X had enough service so he could comfortably retire. At that point, 3 years ago, Big Company contacted him out of the blue about becoming their "technical person." There was a long period of courtship, but in the end X joined BC and took leave from the university. X is a distinguished member, with a wide swath of contributions.
2. X is making a significant contribution to BC, although proprietary concerns mean that I don't know the details. X is very much appreciated there.
3. While the university would not want to lose faculty of X's stature, it surely redounds to the university to have one of our faculty in his role at BC. Some departments have a faculty that is hard to keep, they are bid away by other universities of great prestige.
4. I believe that many faculty would be given a new lease on professional life by going out in the world. This is not about age. Some faculty have languished, others who are productive--could find a new way of contributing. They might take a leave or terminate or retire. I am less concerned here with faculty that leave for other universities or move on to administrative appointments.
5. X's offer from BC came unbidden. Put differently, faculty who might have terrific opportunities may not realize it. I don't know how the university can make faculty aware of these sorts of opportunities, but I think it would be a good idea. I am less concerned with our most productive faculty as I am with those faculty who are languishing. I don't know if deans can be useful here. We don't want to push people out, we want them to have very tempting opportunities.
6. More people should go into governmental service, the private and philanthropic sectors, etc. (Our faculty have served in State, HUD, WHO, NSF...) It's good for them, and good for the university. It is fashionable to talk about start-ups in engineering and the sciences and medicine. But here I am thinking of large bureaucracies.
I have no idea if this is a useful suggestion. Some fields may not lend themselves to other opportunities--except during times of national mobilization (as in WWII). But I think it would be valuable for faculty to realize there are possibilities beyond tenure and full professorship, whether for a short term or termination.