There will never be a "World War 3".
Terrorist incidents will increase around the world and state/regional conflicts will continue, along with the increase instances of cyber attacks on western nations.
But no we won't have a WW3 like the first two with battlefronts, taking over land, gigantic land armies etc., the world has moved on from that.
I can't see any major alliances forcing any sort of all out war before 2100.