In many many many ways this Chinese system is more resilient to the downsides of aging compared with the western individualistic lifestyle.
The primary issue these days with grandparents taking care of kids is that for many people the jobs are no longer nearby, but in neighboring provinces. Parents leave for years at a time, only returning during the Fall and Chinese New Year breaks. It puts a lot of pressure on the older folks.
In my mind China will be resilient less so because of how families work, and more because of the investments they're making with regard to automation and an expansion of social welfare policies.
Indian families are also similar, but never before (at least in India) so many young people have to work away from their home (normally some small town). This puts enormous pressure on young, double income couples in cities.
Let me rephrase that so it's clearer:
"in China. Children MUST take care of their parents 100% FINANCIALLY in old age."
Because of the former one-child policy, that means you're it.
This is a problem for the Chinese military and police, because if you're a one-child, you're very risk averse.
This is seen in Chinese police allowing people to drown instead of even getting their feet wet.
"Chinese police and onlookers watch a girl drown"
This might have been feasible in the past, with multiple children, but now, the woman becomes part of her husband's family or vice versa so(but I presume the former, since having a daughter is so undesirable in China), 50% of the parents get the short stick?
Those children then grow up seeing the hardships and stress of their parents, who complain about how expensive they were and now they won't be able to retire and decide to either wait for things to get better before having children or not to have any at all.
Then the elder statesmen complain about low birth rates.
Until the United States creates policies so that someone who works 40 hours a week, regardless of the job, will be able to retire and afford healthcare, only the top 10% of earners ($150k+) and the extreme poor (medicaid, food stamps, subsidized housing) will have more than 1 child.