The possibility of everyone accepting anyone AND everyone regardless of differences would actually make connections easier between other nations, cause less problems due to religious differences, and would pass off life for everyone as a more peaceful world.
Another possibility I would like to see changed is a more united form of technological advances. We've seen in the past at how different nations compete to try and push the barrier farther. Imagine of the possibilities of future innovation if there could be a change could come sooner like the google glass! The space race would have been much more successful and could've came quite sooner. More jobs could easily be created with the united nations or the world powers setting their sights on the same goal for the greater of the planet.