To be honest, I think tensions the world over have been increasing. Individuals have been trying to consolidate their power bases the world over only to be slowly beaten back with increasing belligerence by their inhabitants. When people say 'UK' most people think of it being Scotland/England as the trouble makers, yet there are growing calls for the North of England to separate from the South. For Ireland it becomes a religious problem, so they're well and truly fucked.
Spain has a serious problem with Basque.
France has been on the borderline of serious civil war for the last two years.
Bosnia is still waiting for the UN to look away for a moment. And Kosovo will probably join in at the same time.
What's left of Russia hasn't sobered up enough yet to be a majour issue, but all gloves are off when (if) Putin goes.
Germany has been desperately trying to cover up it's fascism problem and resurgence of Nazi ideology.
The African continent doesn't need an excuse and it's only corporate greed over natural resources that's (barely) keeping a lid on things.
South America, is pretty much controlled by the drug cartels, so it's anyone's guess what will happen there
Myanmar is still chest deep in civil war and again, it's outside influence (corporate and UN) that's keeping it from full blown slaughter.
The EU is hanging on by it's fiscal fingernails, rumour has it Brexit could be the final straw.
Italy is bankrupt (as is Spain) both have basically said they are not re-paying their 'loans' so there is a massive fiscal black hole in the EU's books (which is another reason why it can't afford the UK to leave). And the current 'leadership' is kicking the can down the road in the hope that they will have left (with pension) by the time it can no longer be kicked.
Really, when you sit down and look at it Things don't look good.
And on top of it all, you have China doing things their way, because they know no-one can do anything about it. Currently they are on a not-so-secret-land grab.
Japan is quietly sitting next door shitting it's proverbial pants because it's in China's sights.
I think when it kicks off, a lot of countries are looking at evening the score with neighbours.
Russia and America used to be 'mummy and daddy' and would step in and stop squabbles amongst the kids, but mummy and daddy have divorced and daddy has developed a split republican/conservative personality.
If no nukes are used, then I think densely populated areas will be worst affected, so those counties with the highest proportion of people per mile will be the places to crumble first.
There's been too much corruption at the top for too long, and I think society is heading for a reset.