You evidently have never been based at DFW where the numbers who don't want to fly, but will neither quit nor retire, are legion.
We've even got some at SLT that drop every trip every month (or as many as they can). If all those who don't want to fly actually left (by whatever means) we would not only not be offering leaves, we would be hiring again.
I could't have said it better myself...Thank you Jim for speaking the truth!