Vivian Maier also, like Winogrand, left behind a vast amount of unprocessed (and nearly destroyed) film. It is now being developed and scanned after her death.
This also brings to mind another interesting point. Usually photographers themselves decide what their best or most desirable work is, and print and exhibit it accordingly. If your film is processed after your death, then someone else's view of your best latent work is being showcased to the public. Imagine walking through an exhibition of your photographs, but never having seen most of them before! ... Especially years hence, when most of your memories of taking those particular shots have faded from your mind.
A very good point and this is a different twist to its use. I suppose I was thinking in my OP as using undeveloped but exposed film as in the same way a musician may use silence within their music, or perhaps a film maker may run a sequence of black within the story of a film. I think to use this concept effectively in exhibition, it would perhaps need to be placed at the end of a series of displayed (printed images) on a very specific theme with the undeveloped roles/cassettes identified as a continuation of this theme. In that way it would leave the viewer of the displayed prints asking questions about the content of these in relation to any artistic development shown in the final image on display, as I believe someone mentioned an unfinished symphony.