Why do you think it would be nuclear? I actually believe the mutually assured destruction principle is a pretty good guidestone at present to see where the likelihood of a real full out nuclear war erupting.

More likely, I believe we are entering a new era of warfare where the surface area of the battlefield covers an ever expanding multi-dimensional space wherein the new battlespace will revolve around information gathering, behavioral analytics and overall just "mastering the human domain". If there is a war I believe it will be coordinated between countries with the intention of diverting the energy of an increasingly angry population to a common enemy who can be blamed for the problems they experience.

I honestly think the head of state in most countries actually see much more similarities between each other than they do themselves and the proletariat