Nice one, McG., and more thoughtful than I expected. I was thinking more in terms of a skit, but I like it.Evidently, as I suspected, people have been leaving for a long time. Reminds me of Brendan Behan's quip about the split being the first item on the agenda of every organisation in you know where.
Perhaps rather than a song we need a whole grand opera in which successive lead characters stand in the doorway singing long arias in which they repeatedly announce their departure, in counterpoint to a chorus which alternately entreats them to stay and wishes them Godspeed!