In terms of industry output, China now produce roughly 50% of the world entire heavy industrial outputs, and they retail markets size is also the world highest, roughly 2X or more than that of the second largest, the US.
China today is very comparable the US before WW2, whilst US today is quite comparable to the some european powers before WW2: China enjoy a huge advantage in raw industrial and economy power (vastly underestimated due to currency distortation through), whilst the US enjoy a head-start in terms of international political influences and military power,and spend alot of more on maintain their war machines ( The US spend 30% of their state income on military now, just like the European powers did before WW2, whilst China spend only 7-8% of their state income on military, just like the ratio US spent before WW2).
When China start to build a world-dominating military power, it wont take long before the US realize there is no chance for them to win, kind of any european countries were hopeless against US in WW2 when both ecomonies turn into war-like mode.