It is an important variable. But a more realistic picture needs to factor in:
1. median IQ
2. skills
3. future unfunded liabilities (welfare, pensions, public health, etc)
China has demographics collapse like the West but they have high median IQ, high skills, and almost no unfunded liabilities. Meanwhile, Western IQ and skills are dropping like a stone and they have trillions in unfunded liabilities. And any attempt to fix it is either a drop in a bucket or going to trigger massive unrest. Just see what happened in France a year ago.
I hope China learns this lesson an makes some changes. At least they have a bit more runway to do so.
I think this really depends on how you define unfunded liabilities. China, for example, has mostly not established liabilities because the social systems for retiring are a joke. People instead save personally and shovel those savings into real estate, but the real estate market is collapsing/collapsed because it turns out all that retirement saving driving up the median-house to median-income ratio to 40+x was not sustainable.
To put in perspective how bad that is, cities the West considers expensive:
Paris is 17x
London is 12x
NYC is 9.7x
San Francisco is 9x
---
Shanghai is down from peak but still at 33x, and that's a correction. Either people still can't afford to buy homes, or a large class of homeowners will become destitute elderly people and all that entails for social stability, or the government will have to make up the difference somehow.
I’d also add that China actually does have future pension liabilities. China’s past one child policy is causing the pyramid to quickly go from 4-2-1 to 1-2-4 in terms of ratio of working to dependents; and young people are already not participating in pensions because they think its highly likely the systems will go bust and they won’t see a cent of their contributions.
I hope China learns this lesson an makes some changes. At least they have a bit more runway to do so.