I strongly believe we're close to World War III like never before. The US, China and Russia and a League of the Arab nations will play a major role. With nuclear weapons and other sophisticated weapons at hand, it will wipe out more than half the population of human race.
There are more than 10,000 active nuclear war heads in the possession of various nations right now. If all of them are used, then it is quite possible that more than 50% of the human population will be exterminated. The major urban centers will be left without life.
Maybe 50 years ago that would be the way to look at it.
But today you have several percent of people from any given country distributed in other countries, including hostiles.
Today the issue is "issues", not nations. If country "a" wanted to attack country "b" and both had nukes it would be a simple matter to land a nuke, or have one prepared in a location, to cause harm. No need for $50 billion super stealth when fedex or ups can deliver overnight, war can wait 24 hours if you need to nuke a country.
There is a benefit to national puppet struggles, in that it serves as a proxy for individuals, a person identifies with country 'x' etc.
The next nuclear use as a weapon will probably be by a small group with a very good cause, unless governments start cleaning up their acts.