China's access to leading technologies and technologists is absolutely unparalleled. The amount of Chinese students that are publishing some of the leading CS and ML research from the best universities and corporations worldwide is staggering when compared to all other nations.
China isn't 'Closing up' they are pushing people to use the services that they control and have insight into. Consider that Tencent, Baidu etc... all have major offices in SV, Seattle, LA etc. Remember the story from yesterday about the Chinese ADTech company giving $3M salaries? That's just growing.
Unless the US, Canada, France, Israel etc... closes the visa program for Chinese workers Chinese companies will continue to be relevant and innovative - and they will likely grow faster with more tailored services because, China has the biggest capabilities to mine user data - more than any other nation by far.