War is unpreventable as nations disagree on ways governments should be run. Religions differ and that will always cause uneasiness between groups. Rocithomas claims that it will end because we have atomic bombs. By the time we have world war III we will have more experienced space travel, and further weapons developed, making this statement invalid. Due to more technologies being developed I doubt that atomic bombs will be used because of MAD. It would be a soldier and robot war.
I think sometime in the next century there will be another war, Because there have been so many terrorist attacks for example the bombings and shootings in paris, there have been school shootings, the shooting in San Bernadino. I think that all of these will lead to a war. Also Donald Trump is making lots of controversy with Muslims. I also this ISIS is causing trouble too.
World War I and World War II were mainly fought in the Western world and in some ways World War II was an extension of WWI. There have been other broadly fought wars before it. I believe that if another war of a similar scale is fought it won't be called World War III.
There will be a hundred more wars until world peace, as Bobfcsoccer said, ISIS are stirring up trouble. But the world has had a taste of a world war, twice even. So they would have learned. And even if their is a war, it will end before it will start, as we have atomic bombs.