USA will always be on top,(sorry if I sound too-american) no one else has the natural resources we do. Our dirt across the mid to northern section of the country looks like it is soaked in oil because its so fertile. We have almost every metal there is available in the rockies. We have lots of land, coal, technology, free market society, tourism, lots of trees, very little desert area, efficient freight lines with the great lakes, mississippi river and its tributaries. Oh, and vegas! The only way we would fall below any other country would be a collapse in the government, or something like an explosion of the volcano under yellowstone... but that would eventually affect every country in the world.