WW3 is already happening. It's just called all sorts of different names, and it's happening in the background.
It is not happening in the same way that previous world wars have happened. I really don't think what is happening would even be considered to be a world war. What is happening today is a number of proxy wars when a very small group is funded by many other countries. These proxy wars are very localized.
What a world war really is many countries allied with eachother who are fighting against many other countries that are fighting against eachother. The war zones will not only be spread across countries, but across continents.
To answer the OP's question, no nukes will not be used. The reason for this is because a world war will never break out because of nukes. Countries are too afraid to go to war with eachother directly because of how close to nuclear destruction we are even without war.
