China as leading innovator, and as challenger to US hegemony?

To what extent has China over the past decade leapfrogged beyond ‘factory of the world’ (scaling up technologies developed elsewhere) to ‘leading innovator’ (starting up technologies developed at home to produce new-to-the-world products)? To what extent has China’s size, economic development, and geopolitical influence reached the point where it is challenging the US for hegemony? The essay gives a qualified ‘yes’ to the first question, a qualified ‘no’ to the second.