Ok, one question: If the quality of the papers being published isn't very good, as you seem to be suggesting, then how does China's increase in scientific output help to enrich everyone? It would seem to me that science as an enriching process is contingent upon quality contribution; the contrapositive of that statement being that a lack of quality necessitates a lack of enrichment.
Might I also observe that the statement "quantity of papers isn't the same as quality" applies just as surely to the US as it does to China. You might counter that, given the current state of affairs, the US produces papers which are obviously of higher quality relative to China, but that's really beside the point. The article isn't really making claims about the current state of affairs in China or the US, rather, it's making a prediction based on current trends. To me, making the claim that the US will maintain its superiority in terms of quality relative to China is no less bold than making the claim that China will significantly narrow that gap or close it entirely in the very near future.
Might I also note one other point of interest concerning whether or not China's overtaking the US is a bad thing: it depends on your perspective. From the Chinese perspective or that of broader worldwide community, it's probably great that China is forging ahead; after all, this will potentially lead to beneficial discoveries and applications around the world. However, from the US perspective, things are less optimistic. Will the US benefit in some ways from China's scientific prowess? Yes, absolutely. Will the benefit to the US from China's new scientific lead outweigh the benefit to the US of having the lead? I'd argue that it won't. I say this because I believe that this will act to reduce the US's credibility as a worldwide innovator and producer. Once that credibility is diminished, things like foreign investment will (continue to) shift from the US to China. The US already has an image problem with much of the rest of the world believing that it will be overtaken by China or someone else sooner than later. If China surpasses the US in scientific output, this could snowball into broader doubt that the US can actually produce something of value that China cannot (at less cost as well). Also, let us not forget that the US carries an enormous debt, and that this debt is essentially an IOU promising some repayment eventually. How do you go about repaying that debt? The way this has been done before is through the manufacture of products or supply of resources that the rest of the world wants. So if you're a nation holding that debt, and you see that the US's capabilities to manufacture, or even invent new methods of manufacture, has been diminished, would you believe that the US's ability to repay that debt has been unaffected? Or, would you demand higher interest rates as the debt begins to look riskier? At some point, these debts will need to be addressed and the magnitude of the debts depend, in my opinion, on the capability of the US to out-innovate its competitors (and they are competitors). Since the US is loosing (apparently rapidly) that edge, I'd say that China assuming the lead in scientific output is indeed a bad thing for the US.