The birth rates levelled off now? So the population is likely to have stabilised at 9 billion by 2050?
There's enough land around.We can agriform most of Africa, Siberia, Canada, and Greenland with Megaengineering projects. Throw in more efficient farming practices and Aquaponics, and we can feed everyone quite easily, with some left over for nature. Maybe move our housing and industry underground (I had a design idea for underground housing with a court yard).