I’m with the glass half full people. We need to reduce the population of the planet, and reducing the population of the heaviest consumers and CO2 emitters is a bonus.
If you look at other countries where there has been a fall in fertility, the increases in productivity in unit labour have outstripped the increase in ratio of workers vs non-workers in the economies, such as Japan.
I agree with the comment about further automation everywhere, that will do to the rest of the economy what mechanisation and open cut mining did to the coal mining industry and labour force (800,000 1920: to 65,000 2015: to 20,000 projected 2025).
Declining fertility leaves more resources for reducing income inequality and skilling up the entire work force and saving the planet.
You need to explain why even replacement fertility is good and why increasing population is sustainable for the planet, especially we who consume and emit more per head than anyone else in the world (especially if you put carbon transfers on all the crap we buy from China etc, which makes China a far smaller emitter and us a way way bigger emitter grossly and per head.)
Cheers!! Look forward to the longer response post.