Whirlibird, I have some agreement with you, WWIII will not be a nuclear war because everyone loses so it will not happen. Now will one of the big three try something to take the grid down in a way that it will not point to them, YES!
This will be blamed on Al Qaeda or a small country like Iran or North Korea or another group that no one cares about. The way the grid gets taken down will be given to one of these group from Russia or China. That is what I think.
So it will not be a WWIII but it will be bad.