On December, 20, the Electoral College declares Hillary Clinton as the winner of the US presidential elections. On the 21st Texas declares independence from the US ("come and take it"), a few days later other redneck States such Arkansas, New Mexico, Oklahoma, etc follow Texas' lead. New York proclaims itself a Free City of the world. Dollar crashes, markets panic, banks closed, Congress and government dispersed, the UN peacekeepers are deployed in Washington DC, and finally the US disbands and disintegrates
This is the end of a united states but not the world and not even those separated states. Strange thing is those states may be better off and more free to do honest and profitable business when loose of the 20 trillion of federal debt and crushing burden from endless political regulations throttling trade.
This is not even a crash scenario, this is a glancing blow at worst and to me I feel its a positive scenario for those people bearing the weight of government currently, ie. the ordinary people and majority of USA and any dollar connected country. Due to the inflationary exporting policy of the federal reserve, this event also brings a positive to those no longer ruled by a foreign power and a reserve currency devoted to serve one party in one capital in one part of the world . Again its not a crash for most countries, some western systems may falter as they lose the bonus dollar advantage.
The important point here is the majority of population does not live in one country or one state even, its become more distributed more able to produce widely so any break down in such a large biased system is a world positive. Certainly longer term and feasibly even short term you will not see the 1929 type crash some might expect. A very brief example is the election of Trump, perceptions were very negative and market futures fell but the actual market open saw a rise not a crash. This strange disparity might also be true of a much bigger dissolution of the states or any similar big scenario you think of, most of the world is not living in a 1st world country and most of the world is very capable of being productive anyway. The current system is a restriction to world production, dont be one sided in your thinking to imagine the market cannot navigate a big change and even profit