We are America. We are a nation created by an idea, composed of people who did not start out as neighbors and who couldn't speak the same language, the fortunate child of change.
If we do not remain a nation of liberty and opportunity, available to people from all over the world, constantly reinventing ourselves, we will not remain a nation.
This will be true even if we end up the only state with access to fossil fuels and the only state with weapons of mass destruction.