A modern day Carrington Event, a meteor strike, an economic collapse... the mechanism won't really matter if the world crumbles around us and the niceties of civilization begin to fall away. In such a situation, strength and safety will be found in numbers, so which skill do you possess that would make you valuable to a group of people? Our skills will become our currency, and being proficient in Worlds of Warcraft won't exactly be a marketable asset! Medical training or engineering knowledge? Gold.