All this reminds me of a saying in Italian, which I came across in my futile study of the language - Morto un papa, se ne fa un altro. Call that phrase an eight-word summary of the above post.
Literally, it means "when one pope is dead, they make another one"; but it is a proverb (apparently) and expresses something like "nobody is indispensable" or "everyone is expendable," that idea. Think Le roi est mort, vive le roi.
In keeping with the above theme: the Italians also have a saying ogni morte di papa (lit. "every death of a pope", every time a pope dies), meaning "once in a blue moon," "on rare occasion." It strikes me as just a bit morbid, but now that I think of it, so is "The king is dead, long live the king"....