When asked about what could happen, there was some talk about a default cascade leading to depressed prices [waves arms] and a grocery store can't make payroll because they can't find a bank to give them a loan secured against their inventory. Now, I don't think he's wrong that we could see grocery stores not making payroll, nor that a default cascade could lead to that. I just think that the arm waving part is what saves us all. If things really do get that bad, then new systems will be formed of necessity. For example, some of those grocery store employees could take a portion of their pay in store credit, micro-lenders could come to the aid of the store (micro-lenders that include the employees), barter will happen, illiquid assets will be traded, and so on.
Not that it will be pretty, or that their won't be real pain, but there are ways to eke by.
Also, I think the most telling comment of the interview was when Mandelbrot said that we couldn't calculate the odds of a catastrophe like this. Taken to it's logical conclusion, this kind of means that we can't tell if we should even be paying attention to these two on this matter. (I know. Mandelbrot. But even Homer sometimes nods.)