Those demographics don't matter nearly as much over the next 10 years as they do over the next 40. But I agree with you that most predictions of China taking over the world seem to completely ignore demographics - which is dumb because it's one of the most predictable parts of a country's future.
700M Chinese citizens who live on $140/month income.
500M 65 year olds by 2050 (money flows up in Chinese society. One grandkid pays 2 parents who pays 4 grandparents, since it's a one child society) Oh and no social safety net. you think CCP members care about the plebs?
The most probable reality is that neither the bulls, nor the bears, have any clue what will come in China. They probably make less money if they admit that though. "There's too many variables to be certain." Probably sells less than, "The Secret to the Future of China!" So they have to go one way or the other to justify their paychecks maybe?
You could say the same about any undeveloped country, but in reality only a small number of countries have successfully transitioned into developed status - Japan, Korea, Taiwan, Singapore, HK. It's not as straightforward a process as it would seem at first glance.
What countries do you know of that have China's educational levels, manufacturing capacity, natural resources and political stability that didn't make it into "developed status"?
I'm thinking about Italy: after WWII, the country was still mainly rural and much had to be rebuilt because of the war. And yet (with the help and blessing of the US, then much interested in keeping Italy on the side of the West) it experienced twenty years of rapid economic growth. It had a good education system, and it had manufacturing capacity (FIAT, Olivetti, Montedison, Ansaldo, Zanussi...) and especially, it had tens of millions who wanted to buy their first car, their first washing machine, their first tv, their first telephone, or wanted to rebuild their houses with modern techniques. It needed workers for the factories and sourced them from the poorest parts of the country, triggering an internal migration and further growth in the economic capitals of the country. China seems to have been in the same phase for the past 30 years, and it's so big it can keep up at the same pace for other 20 or 30.
Nope, these people (farmers for life, migrant workers with no education, people living in abject poverty, etc) are stuck.
If there were actual growth in the economy, China would not outlaw hong kong citizens from leaving to go to England, creating a wall with myanmar to prevent citizens from escaping to there, having concentration camps to force uighurs to work for free, etc.
Fearing both unemployment brought on by technological advancement and population graying is a hopeless contradiction. Either one, the other, or neither will dominate.
I bet on tech, especially because negative population growth will put upward pressure on wages.