Well, it has happened on a smaller scale somewhere in the world every decade for most of human history. Weimar Germany, Zimbabwe, Argentina a couple of times, The Great Depression. It's the rule not the exception. Only this time it is for all the marbles.

Most digital currencies are immune to the shutdown but BitShares is the only exchange on a blockchain that can handle the full load of everybody fleeing to safety. The others will clog up like they do already on the slightest hint of a new ICO.