China has a long, long way to go. Analysts are talking about China becoming the largest economy between 2030-2050, but the world will be a completely different place.
The USA isn't just dominant because it's the largest economy. The USA is dominant because it's by far the world's largest economy. The USA's economy is equal to China's, Japan's and Germany's combined. The USA is currently equal to about a quarter of the world's output.
It's those kinds of statistics that make a country dominant, economically speaking. And, it's those kinds of statistics that I believe are not possible ever again, for any country. The world of 2030-2050 will be a world of equal powers. The west (NAFTA EU) will still have a lot of influence in the world, but they will be on equal footings with China, Russia, India, Brazil, as well as other trading groups such as ASEAN.
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As for the whole "superpower" thing, I direct you to one of my previous posts - http://gamrconnect.vgchartz.com/post.php?id=3455532
