My colleague was tragically struck by a car and killed about three months ago. The course suffered an immense blow to the knowledge capital it had - but due to the fact that we had planned to mitigate against key-person risk by pairing - the course was able to survive and retain a fair bit of the legacy my colleague left behind.
I just share this to say that the getting "hit by a bus" scenario is something that, much like this post, we throw around in jest and treat in a laissez-faire fashion. The fact is that it is a tragic, unimaginable, event that does in fact occur from time to time and something I will take seriously for the rest of my life.