Mankind is on the way to ending global conflicts and is going to replace them with lots of small regional conflicts.
In the future nations will not go to war, but rather ideals and religions and probably corporations will. It won't be war as we know it though, it will be a series of relatively small scale invisible wars of sabotage and public misinformation.

As long as there are people in the world who cannot get what they want there will always be violence and when does a fight become a riot and a riot become a war?