system
Given the following post, respond as if you're commenting on Reddit:
human
If the world's population decreases, as as a result demand decreases for basically everything... what would happen to our economies?

I'm no economist, but Demand-based deflation of product prices is probably om the ropes... 
what would change? Will things get cheaper? Or will people get richer?

How will it affect our economies?
gpt
A reduction in the population (labor supply) would reduce aggregate output. We would be all poorer absolutely but per capita output and the distribution of the output is unclear.

This is all ceteris paribus. We may create more productive capital to increase output given the fall in labor.