I sense a second cold war to be brewing between the Commie Chinese and the Capitalist Americans.
I won't correct you on the whole "China's not communist!!!" thing since others will, but any cold war will be for rhetorical purposes; we're too dependent on eachother.
China will become Europe 2.0 - we may slap eachother all the time, but we'd never engage in a full out brawl. Except if the victim of the brawl was a third party.
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My First Question: is Will China ever overtake the us and the number one largest importer of goods.
Quite possibly; it depends on how the demographics and economic growth work. It's hard to make predictions, especially when financing gets involved.
My Second Question: If China Does over takes the use in importer what would that mean for the Usa.
Not much. We'd still be a major market, even if second or third(if the EU is thrown in). China would see more appreciation in terms of influence and prestige, but as has been said, it's not a case of the US declining so much as others getting closer.
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On the topic in general, one could make the argument that the "superpower" system is obsolete. During the Cold War, two camps were so heavily dependent on one nation the term had value. Nowadays, everything is so interconnected it has far less merit than before: Europe isn't a wartorn disaster that needs US assistance or else hordes of soldiers will pour over their borders, to name an example.
Interdependence has made the "superpower" label far less meaningful; it used to be a case of total dominance, now it's a case of who dominates what. The EU will steadily rise to soft power dominance, we'll likely maintain our military dominance for a while, and China will likely retain production dominance. We all have our strengths/weaknesses now, whereas originally it was all strength.
China may rival us, but they'd never attack us. Not only is there MAD, but there's MAD 2.0 - Mutually-Assured Depression. We need their cheap goods and they need our money that we spend on those cheap goods.