You have to look beyond just the numbers and assess what we are talking about here. The only way we would face their entire Army would be if we invaded them, otherwise how in the hell will they transport 200 million people without us seeing the movement and stopping it or attacking them? If we were to fight in their country, chances are strong that prior to us going in there we will launch missiles and drop bombs to weaken that army though not as easily, still would be just as we did in Iraq. If we are talking about on neutral ground, then I think they stand the best chance, but again, it will be who gets the most people to the location first b/c again they will not be able to move massive amounts of troops without being spotted and stopped. Last I will say, if we are honestly talking about a battle or war between two superpowers then you know that before either goes down as the loser that there is a very very strong likelihood the one being defeated will launch a nuclear missile in a last desperate attempt to win which will be responded to with one of from the opponent.
On the nuclear weapons issue. The day is coming when these will be obsolete. With a couple of satallites and some mach x missles, the nuke can be destroyed before it hits the ground. In regards to America never falling, what would happen if we had a few disaterous growing decades(eg bad crops, lack/too much rain) My money is on China, but even Brazil, if it gets lucky, can make it.
In reality, Western culture with its representative democracies are the real "superpower". Despite our recent disagreements, the US, the EU, and Japan are too intertangled economically to ever challenge eachother militarily. Russia will soon join this mix. The Chinese will someday be forced to change their government as their people truly join the information age.
By the way, I don't think China would ever be able to successfully invade Taiwan. The Taiwanese would gain air superiority quickly with technology bought from us, and the Commies would be left with only the nuclear option, which they would never dare exercise.
well that's the hope of liberalism and democratic peace. In support of this, it's interesting to note that there has been no real balancing against the post-cold war us dominance. In addition our cold war allies and nato have outlived the bi-polar world. Unfortuantely, the actions of this adminstration has led to the breakdown of some of these allegiances and what could be described in realist terms as the first real signs of balancing against the US. Because of this, i'm particularly troubled that the US would want to call the UN irrelevant, because it along with nato and similar internation insitutions are the backbone of liberalism and the thought that this intermingling of democracies can lead to lasting peace.