RISKS-Digest is a valuable and venerable resource. I find it somewhat ironic that it seems not to have any specific preparation for transition or continuity.
That's a challenge for numerous projects, and I can think of several examples of projects, services, or other institutions which failed on the death, disability, or retirement of their founders. It's a highly foreseable risk.
* https://en.wikipedia.org/wiki/Peter_G._Neumann