Absolutely not. It will never happens, I guarantee.

As John Kenneth Galbraith wisely said in his great work "The age of uncertainty", all wars happened because wealthy people somewhere wanted still more money and this would cause less money for the wealthy people somewhere else. So both sides send the poor people's sons to die to settle who gets the money.

A worldwide war will affect even the richie guys. Do you think Presidents and Prime Ministers rule their countries ? They are just very qualified butlers/housekeepers, administering the big house wisely because wealthy people have neither time nor patience to worry why the curtains are screeching or the populace is complaining. Power is the availability of resources to push your wills down the throath of other people, it doesn't come from gods, peoples, or whatever except material resources. And never did, and democracy is maybe the biggest farce created by the western civilization.

(I can't explain why here, it took me more than 30 years reading a lot about History, Economics and Politics to draw these conclusions. Just explaining why I don't fear WW3.)