I beg to offer a different perspective. During the Cold War era the economies of the super powers we're independent of each other. Actually they were actively rivaling each other. The relationship between The US and China is quite some different. They are economically so interlinked and in bed with each other that starting a war would mean literal suicide for both nations as we know them currently. Suicide by not nuking each other (China doesn't have the capability to nuke the whole North American continent, they would've to settle "only" nuking the US allies South Korea and Japan out of this world while the US could certainly nuke China off the map) but by causing internal revolt by the people in both countries.
In the US the people would not be able to enjoy the relatively comfortable lifestyle based on consumerism that has lasted for last 70 years or so anymore as it's all based on global import of goods, China leading the pack of exporters of course. Government that deprived the people from this privilege would soon be thrown out by democratic process if the nation is strong enough internally that it can function by its most deeply rooted ideals even during really serious war time (China would be quite a different beast to beat than Saddam or a few thousand bearded men living in the barren mountains) or if not, then by force. In China internal revolt is maybe more difficult due to the authority-respecting/fearing mindset of the people established by authoritarian governmental mechanisms that have been in place in a form or another for thousands years there. But maybe crushing of the humble Chinese dream (i.e. moving from the countryside to the ever expanding megacities of the coastal area in order to seek better life), that is completely facilitated by the fact that China acts as the factory of the cheap goods for the world, something would happen. And that something would certainly not be in the interest of the current ruling dynasty of the long chain of dynasties that have been ruling China like forever.
So if the economical ties would be cut down by the war, both societies would probably either just collapse as nothing would work as it used to be, or better, leaders who would end the madness would gain the power. But no-one would know what would be the end result of this global turmoil. Global, because we're all in the same global economical boat. The world is quite a different place now than in the 70's. It's much smaller and balanced. Like it or not, The US is not the same super power it used to be when the world was very polarized as The US and USSR were trying to divide the world into two factions ruled by the said true super powers. The economical downward spiral of The US, the rise of China, India, Brazil, Indonesia and other big emerging countries, re-rise of the Russia led by the Putin's mob clan and the unification and even federalization process on-going in Europe means that we've become much more converged globally as instead of two superior powers compared to others we have a number of more equal powers with significant global influence (economically and politically, not militarily, The US is the only nation left with true military presence globally, too bad they can't afford to put it in use anymore in any significant campaigns even if needed).
Why China is arming then? To counter the strategic shift in The US policies, of course. It's no secret that The US is shifting its military focus from the Atlantic side of its home continent to the Pacific side, and at the other shore, there's China. In fact they've been very open about it. And why wouldn't they? If the global economical balance is shifting from West to East, the troops should follow of course. The flow of goods must be secured. How ever, it doesn't mean that the armadas with ever increasing weight in steel and number of guns and missiles patroling the same waters have to encounter each other in an inevitable hot war. The troops are there to secure that no power is dominating too much. It's a pissing contest, basically.
Nukes are not holding the status quo anymore, trade links and economy is.
Backed up the system lately?