That's not how a post mortem works. You want to identify the root cause of an incident and any factors that increased the impact or prolong the incident. Solving for every possible scenario is how you end up solving for nothing. Playing the "what if?" game leads to an infinite set of potential problems and time, being finite, means you can never succeed

When we've solved for the current problem, we can address the next worst thing. We won't know what that is until it happens.

We could also solve for knife and sword attacks because there was that one time in Japan where someone murdered a bunch of kids or chainsaws because of that other one time that guy had a chainsaw but we do more by staying focused.