Not just a bloc of NATO countries, but also with Russia, which seems to be eagerly invited into organizations such as G8 (= G7 + Russia). With Russia, Ukraine, and Kazakhstan, the total population of such a bloc is 1 billion. I can forsee the US, France, Germany, and Russia soon forming a proto-military alliance, to give them the option to counter-balance China if they need to one day.
And of course the US, unlike China, has immigration as its foundation. They could accept, say, 20 million educated and/or wealthy immigrants from China over the next 20 years, with no shortage of takers ( http://news.ycombinator.com/item?id=2660178 ), which would strengthen America and weaken China.