What if the backlash over the downing of the U2 spyplane escalated to the point where the USSR declares war?
Via cold-war military doctrine, it's safe to assume missiles would be launched by one of the war parties prompting a swift response by the other.
Considering the world wouldn't have ended via nuclear apocalypse, (since the size of the combined stockpiles in 1960 couldn't achieve that) once the stocks are depleted what would be the shape of the world in the aftermath?
Does the US and the USSR survive?