I think that hiccups in the transportation / supply system can reveal problems with how companies today use the idea of "just in time" for inventory and supplies. When a ship hits s torm, when a train derails, when there is a traffic accident or delay, the goods make not get to wehre they are needed "just in time." However, I think seeing the collapse of a society because the trucks are delayed is a bit much. Of course, if the system slows down and becomes less predictable, then the idea of "just in time" becomes harder to do and use. But if things get really unpredictable, I think companies would revert to former systems and carry some more inventory.

The companies and economies however are going to take a hit because of it. However, if it was the deteriorating infrastructure that delayed supplies, you'd have a sign that the economy was already having difficulty. The falling apart of the ability to transport safely is a bigger deal than the timing of it.

I think TEOTWAKI can come for a number of reasons, but it will in all liklihood not be solely one reason. The problem is we do not have many examples to look at for the fall of a civilization. Rome fell apart over a long period of time, but we live in a very different world. The Mayan and Mycenaean civilizations both fell apart, but I think the evidence as to why is very sketchy in both cases.

Preparing for TEOTWAKI is something most post on this forum have though some about and many have tried to prepare some, just in case. That's the whole idea of preparing, just in case something happens. The Dark Ages were not fun to live through relative to most of the Roman times, but the human race survived, thanks to some who had short and/or hard existences. Who knows what happens when our societies fall apart.