Yes, there will. There's never been so much as 1 day in all of recorded human history when there has not been a war going on somewhere in the world. Mankind wages war. That's what we do. It is inevitable. To those who think it will never happen, I say "never is a long time".
Albert Einstein said "I do not know with what weapons WW3 will be fought, but WW4 will be fought with sticks and stones".