What you are asking is difficult to predict. It is uncertain enough if one person will master their emotions and behave at peace with their neighbor, but it becomes astronomically unpredictable in the case of the world at large. In the past, there were docile civilizations who lived in peace with one another. You have to wonder if that was our natural state and we have evolved into something hideous or perhaps eons ago people became docile because they learned lessons from some tragedy in the world. I think it would take catastrophe on a global scale to teach mankind to live in peace again, considering many people are so hard headed when it comes to peaceable social skills. The Bible (whether you believe in it or not) has a lot of verses dealing with common sense, especially in the Old Testament. The Bible mentions how we should be slow to anger, which is a result of how much patience and empathy we have. Sadly, people today are easy to agitate and have seemingly been taught only one way to deal with things, and that is; an eye for an eye. Of course the problem lies in whenever two or more people have a difference and become hostile to one another. It takes two parties to have a war, but only one to end it, and I am not talking about the winner by might.
I think that world peace had by man cannot come about unless mankind changes sincerely on the inside. When and how this will happen - your guess is
as good as mine, but perhaps that is the next step in our evolution. Maybe it is a spiritual or supernatural event that is scheduled to occur at some
pivotal point in the future, when we are ripe.