Long term compare the People's Republic of China (China) and the Republic of China (Taiwan) after the war based on per capita GDP and the mainland is still catching up. The CPP maintained power after completely wrecking the countries economy, so a period of stagnation seems unlikely to be a major issue. More recently you can see how the CPP is placing Hong Kong’s economy as a lower priority than increased control.
While dictatorships like China can fall surprisingly quickly, I doubt slower growth is that critical of an issue.
Moreover rising expectations beget rising expectations, and the genie is out of the bottle.
I don't foresee a revolution either, rather a perestroika movement that will be forced from below but embraced out of necessity from above. As the video said, all of the energy needed to address domestic unrest will drain from China's ability to project their national interest.
The one child policy only accelerated the decline. When it was lifted, birthrates hardly budged.
Every developed country is a slow motion demographic car crash. China is in a bad position, I'll grant, because the CCP's legitimacy depends upon demographic dividend-scale growth rates when the dividend has already peaked. Democratic countries have pressure release valves built into their political systems that China lacks.