I don't think wold peace has anything to do with there being many or less countries. The problem is with individuals. If each person should aim for peace, then the world will become peaceful. What is world peace anyway and who is supposed to be in charge? It is human beings living in the world. So countries are not things, they are occupied by people. Peace is within and not without. You may travel the world and still not find it.
These are some of the elements of peace, whether world peace or individual peace:
living without fear, living a charming life, calm, quiet, truth, justice and many more.
whatever we expect to see in our world, that will we receive. So expect to see world peace and you shall have it. PEACE!!!