Interesting factoid: about 94% of world oil production gets burned, while about 6% is used as feedstock -- piped into factories to make chemicals, fertilizers and (especially) plastic.
There's been a fair amount of discussion about how to gradually phase out oil in transportation. I haven't seen any about the feedstock issue, though. Go figure. The world drinks a huge amount of oil every day, and 6% of a huge amount is still a lot.
Presumably petroleum products run the gamut from stuff that could easily use other inputs, through stuff that would be possible but very hard and expensive to make without petroleum, to stuff that cannot plausibly be made with any other input. I'd guess offhand that a lot of plastics fall into those latter groups, but I really don't know.
This led me to a few moments of speculation: imagine a future where all transport has shifted to hydrogen (or whatever), but a small crude oil extraction industry stays alive to provide high-end plastics. Which are luxury goods, of course, and status symbols...
But no. The price of petroleum-only products would hit a ceiling once it the price of oil rose high enough to make petroleum synthesis profitable. That would be high by today's standards -- hundreds of dollars a barrel -- but not high enough for plastic jewelry to replace gold and platinum.
Still: soaring crude prices must have various industries looking around for alternative feedstocks. Wonder why we're not hearing more about that.