I argue WW3 happened already. To save time, I don't bother often.
The cold war was a global war with many proxy wars with a death toll of just the hot wars higher than WW1. If you count the cold policy games and exploitation of the war I'd expect the death toll estimates to get near WW2; although, this is not a fair comparison because if you expand WW2 in similar ways it's numbers get much higher.
WW2 didn't get fought like WW1, technology shift. WW3 had nuclear technology and so they fought unlike other wars; also they shifted to an empire of political influence by any means short of nuclear. So today we have it being restarted in an idiotic way by old men; one using subversive spying and conventional war and the other by idiotic hubris: economic and militarily... oddly with both working together to compete for territory to restore past empire. With a successful conclusion leading to confrontation again - hopefully just another cold war; not that it is likely either will succeed before they die.