Predicting a -70% population drop in the US by 2025, and a tremendous drop in military expending:
https://www.deagel.com/forecast
This authors attributes it to Oil production collapse:
https://www.theamericanconservative....in-the-future/
It seems a little bit fantasy to me, but I do know oil production changes can be catastrophic to the economy, and can happen suddenly.
I think if the gov't envisions the situation in time, it could smooth it out by subsidizing the oil industry to make it "profitable".