State level policy has been adopted to increase birth rate. I think it's a kind of late, but it's managable.
Ideal population in China should be around 500 millions - 1 billion. 1.4 billion is too much.
Highly developed society with 500 millions is strong enough, think about it. Singapore only 5 millions.
Population pyramid is an big issue, but China is not US. China is more like Japan. The state will handle it in a very different way than western countries on population decline. China will not allow huge immigration.
Agricultural industry need much fewer labors than 20 years ago. 2 millions farmers feed 300 million Americans. China will gradually be the same.
Trucks, buses, automobiles will be automated. Most banking has been handled by cellphone apps. China is a cashless society now. Most low-end manufacturing jobs will move to ASEAN, and India, Bangladesh, Africa.
I think 1 billion for 2060 is ok as long as they are well-educated, disciplined, innovative and cultivated.