CCP under Xi has reverted to form after some temporary loosening up, but it's still way less autocratic than it was during the Mao era.

Also, the CCP ultimately derives its legitimacy from materially improving the country for the Chinese people: back in the day fighting back against the Japanese and corrupt warlords, now economic progress. Both the Chinese people and the CCP know well what it means if they stop delivering and the "Mandate of Heaven" expires.

https://en.wikipedia.org/wiki/Mandate_of_Heaven

China's demographic decline will take decades and unless the CCP really fucks things up (eg. invading Taiwan and failing miserably at it), it's going to be a Japan/Korea-style slow-motion stagnation, not a dramatic implosion.