You completely disregarded the central thesis of the comment you responded to.
The one child policy means there are no people to do the manufacturing in China in the future. The population pyramid is inverted. You can't do manufacturing without lots and lots of people. Or at least you'll get out competed by your neighbours who have lots of labor.
India's birth rate is also massively dropping. In a few decades, India will reach their peak population.
China invested heavily in machinery and automation many decades ago. They'll be fairly fine.
I visited India a few months ago. Loved it. But I saw construction being done with donkeys hauling dirt and people shoveling the loads onto the donkey's cart with tiny hand shovels. Scaling up from that to the degree of manufacturing powerhouses like China have is not going to be easy.
China investing in machinery and automation means they are moving up the production chain into more expensive and more profitable manufacturing.
It also means they no longer do the cheap high volume manufacturing, which will go elsewhere where the cheap labor is.
This is how it goes. Manufacturing keeps migrating to cheap labor. China is running out of cheap labor and volume manufacturing will find it in East Asia and India and Africa instead, because these places will still have lots and lots of young people while those in China have aged out.
The one child policy means there are no people to do the manufacturing in China in the future. The population pyramid is inverted. You can't do manufacturing without lots and lots of people. Or at least you'll get out competed by your neighbours who have lots of labor.