I agree with jk88cal.
Korea is following what Japan went through with about 10-year delay.
Social phenomena Koreans would never associate with them (such as extremely low birth rate, long recession, losing the momentum of innovation etc) is happening so rapidly. Resemblance between what two countries have been going through is quite amazing to me.
Certainly, China is in better shape due to its population size. However, that large population could be a big burden to even reach the peak time.
Anyway, IMHO, what makes SV so unique is "it is the most desirable location of the world especially for highly talented people". That includes stable political/social system (we should give full credit to Americans for this), large ecosystem with money, weather, (open-minded) culture, diversity, education level of average citizen and etc.
I understand China has large population with talents.
However, would any city in China be as desirable location as SV for global talents?
I doubt it in the near future mainly because its social/political system and air pollution.
Anyway, it would be interesting to see how some of Chinese cities turn themselves into attractive places to live.