Old Chines saying: Separate too long will unite, unite too long will separate. But it didn't mention if separation and uniting is peaceful or not but it will happen.
World uniting is a LONG way off. We as humans still fight for land due to culture, religion, politics, and race differences. It will take some more much painful World Wars (1 or 2 or more) to teach us to look past this and just look at each other as HUMANS and work for ALL HUMAN's interests.