China still has 10-15 years where its economy will not be truly horrible. This is also the time, when European economies also get terrible and the US exists its millennial echo-boom. The only hope will be if AI, robotics and self-driving cars creates an offsetting economic boom or if radical antiaging technology is developed to restore vitality and fertility to humanity.
China will be continuing to leverage the last effects of urbanization. China is at about 65% urban and China can go to 80% urban. China's overall population has started to shrink. China's fertility rate has been about 1.18 for the past three years. Previous, UN population forecasts where China loses the population of Japan by 2050 (dropping from 1.42 billion to 1.3 billion) assumed that China would have a fertility rate of 1.6. 35% fewer babies per year means 9 million babies per year instead of 13 million. The drop accelerates as 2 million fewer girls do not exist to have babies in the 2040s. There is a chance that the fertility rates drops to the 0.8 level of South Korea.
Urbanization can continue to offset the declining overall population until around 2035. The population decline then gets even worse and the urbanization process will be completed.
China will be aging at the same time. China will be going from an average age of 38 now to over 50 years in 2050. The aging population will be a 20-40% hit on GDP.
The GDP hits by 2035 will already be at the level that Japan has experienced from 2008 to 2023. Japan has lost 6 million people from its peak. Economic growth from technology and other factors have barely offset the economic impacts of demographic decline.
The projections for China are worse than current UN estimates. China in 2050 will likely look more like current China in 2070 projections.