You analysis fails to take into account three things; economics, science, and this isn’t how anything works. Because oil, petroleum, petrochemical, are not some sort of Unobtainium, they are just hydrocarbons. The world is full of hydrocarbons. Even you are mostly just hydrocarbons.

Sure all this would be plausible if happened suddenly and all the oil were to vanish overnight or even over just a few years but that’s not going to happen.

What will happen is economics and science. As supply decreases it will become more expensive, as it becomes more expensive alternatives that are currently too expensive will become the cheaper option. Thats it. It’s really that simple. Will things get more expensive sure, but they always do anyway. And a lot of people are going to get rich off of the transition.