powerful. It had the second largest GDP in the world, but hey stopped innovating and investing in its economy. Instead they spent lot of money on national defense. People tended to buy foreign goods because it is more innovative.  It led to economical stagnant and political instability.  The same thing with China's Qing Dynasty. It had the world largest GDP in the world, but the government actively discouraged and punished any innovations.  It led to economical collapse and political instablitiy. 

The current government of China has invested lots of money on economy and techs.   I don't think it will have any problems in the future.  As long as it keeps innovating, people buy the goods. Economy will be growing.