It's one of those things which hindsight commentators will say, we could see this coming from a long way off. But actually, there are many little steps that lead up to a big step, and even then, there are conditions which divert intensity elsewhere. Now, however, we have the fact that developed nations have put 'boots on the ground' in Syria. Or at least, one nation - Russia. There is a lot of strategic self-interest involved.
The Arab states stand around dithering. I mean, did anyone ever expect they would do anything, except in Yemen? There is only one state that has the capacity to initiate an alternative involvement to Russia, but Obama hasn't the stomach for throwing American lives into the cesspool of the Middle East, and who can blame him?
One gets the feeling that huge changes are unfolding from the new war zones, be they through military of humanitarian consequences.
But it's not just the Middle East and terrorism, we also have climate change. Vast numbers of humanity are on the move, and it will only increase. We are entering a period of instability not previously seen on this planet.