Close to impossible? Where does this idea come from?
TSMC has giant factories in mainland China. TSMC fab 10 in Shanghai produces millions of chips for China each year. They're literally next door to China's own SMIC.
Chiang Shangyi, head of research of TSMC, is now head of research for China's SMIC.
SMIC also has complete access to EUV tech thanks to IMEC. It's just a matter of time before China has a working EUV production line.
If the West wants to cut off advanced chips to China, they need to also cut off TSMC and limit IMEC's deals with China, because Taiwan, China and IMEC have an open door policy when it comes to chips and research, tons of people working for TSMC now work next door for China's SMIC. Tons of people who helped design EUV at ASML and IMEC, now work for China's SMIC.
This idea that China can't access advanced chips is a made up fantasy.