The sky is filled with black swans any one of them could set off the triggering of a chain reaction event.

That is why putting these highly risky and leveraged derivatives on an open exchange and sorting out all this counter party risk and voiding those that cannot be  considered valid is so important. It puts a lid on the contagion that could cascade through every country. Might still be banks fail but it will be of their own doing. There will still be banks just not the ones we have today.