On one hand many countries will invest in heavy industry, manufacturing, and fall back to fossil fuels.
On the other hand, economy overall should slow down and consumption of non-essential goods and services will drop.
I’m not expecting any definite answers or numbers, of course, just some food for thought.
Yes, but the opposite way you might be thinking since mass death from war and other catastrophe is strongly correlated with very high birth rates. We’re on track for the global population to stabilize around 10 billion right now, but if billions die in a world war we will probably go exponential again for a long time.