I'm a bit late for this thread, but a little reminder of where we were doesn't hurt anyone.
In the 1950's bomb shelter's were built because people were so sure there was going to be a world war between Russia and the US.
1960 it came damn close to happening with the Cuba missile crisis.
Me in university 1984, the first book I was assigned to had to deal the the ramifications of a nuclear holicaust.
Mid 90-2000's Russia goes bankrupt partially due to their war in Afghanistan. Back then THEY were arming the taliban.
Now the danger is either Iran with a nuclear bomb, or the sale of a dirty bomb to an extremist group. I think either is likely in our lifetime and the real danger is if the later happens, and it will.
So world war? No, a nuclear attack of some kind from someone..sooner or later, yes.
Why? Because we're starting to play a dangerous game of wack a mole and sooner or later, it's going to be apparent that you can't contain everybody (with bad intentions) every where for all of the time.