Well, hte economics of the matter of changing. It's going to cost more to produce in China soon, due to rising labor, transportation, and other costs. At that point, I don't think it'll matter too much if China is set up for it already, the jobs will start coming back on their own. Specially if you add in extra domestic pressure to produce the stuff at home.
I've heard numerous people still state that American's are more productive, so I'm not sure how much I believe the idea that other workers are "the best." Who works better: someone working 20+ hours a day, for shit money, living a shit live, and wants to kill themselves? Or someone working 8 hours a day, for decent money, living a fairly good life, and doesn't want to kill themselves? Factory conditions can mean you can probably force more out of someone, still, but people are who in a good mood and relaxed work better, and do better work. It's why giving employees vacation days helps productivity improve.