In my opinion, the World War 3 will be fought by the NATO against the Russia-China alliance. Even a few days back, China created unnecessary tensions in the South China sea region.
In the world there are so many local conflicts that affect the interests of superpowers that in passing you think about the fact that really the Third World War is not far off. If you really want to know what will happen next, you just need to look at the leaders of the country and their state. You correctly named such countries as China, Russia and the US Well, a significant role Putin But steal in all this situation, Syria and North Korea.
North Korea is very unpredictable. And the leader of this country is strange. It seems to me that the Third World War will begin because of the conflict of this country with some other.