I would expect per barrel it would become a lot more expensive if you're not extracting at the same scale. $1000 a barrel or more if you're only extracting 5% of what we are now, for chemical processes.
I'm thinking scenario where world will be using 300% more oil by adopting 50x more plastic use for large scale application with oil selling at 1/3 of the price, loe enough to break models of more expensive extractors so cheap producers have near monopoly over commodity. All very hypothetical. But imo essentially everything you see in built environment could be covered or finished in plastic if performance / price right. I can imagine world where we use much more oil.
