There was also a government during the collapse of the Roman Empire, which surely must qualify for any reasonable definition of a 'collapse of global civilizati

There was also a government during the collapse of the Roman Empire, which surely must qualify for any reasonable definition of a 'collapse of global civilization'. The US going through something akin to what happened to the USSR would be a similar event for today's world, given the massive role that the US plays in the current world order.