World peace will come when people have absolute assurance/certainty that their way of life is sustainable. In order to create world peace we must find the best model to create sufficient sustainable resources for a projected future population. Once this is achieved, people must know that they have a right, enforced, to their given amount of resources. I think that the best practice for this would be to assure everyone an upper middle class life (as defined by the standards right now) and allowing them to improve upon that if they wish. If the population wishes to increase, they must plan to have sustainable resources for the projected population.
Once our own world is stable and peaceful, we must colonize the Universe. Eventually our sun will burn out and the black hole at the center of our galaxy will engulf our planet or what is left of it by that time. I am using an optimistic theory of the Universe, that it is ever expanding and will not come down to two giant (or tiny) black holes competing for the last of the matter in the Universe before one engulfs the other and explodes, having nothing outside of it, like the big bang, creating another universe and renewing the process. Assuming that this theory of perpetual expansion is correct and we will not be wiped out regardless of what we do, we can sustain the human race and what it evolves into indefinitely.
We must continue to develop weapons for defense, but never for aggression. We can colonize uninhabited planets, inhabited planets (if they are willing to accept us), and create livable spaces like self containing ships or even planets. We must reach a point where we absolutely know that the human race or what it becomes is going to be able to exist forever (this comes with keeping the resources they use sustainable). This population will have one job, constantly improve conditions until they are optimal, sustain these conditions, sit back, reproduce, and enjoy life until death. This is the absolute end, bliss (for me at least).