@W.S.Gossett on "Gas"
"a surprising number of firms/industries which rely on [gas] as a chemical feedstock. That is, not using it to boil water for electricity, but to convert into other chemicals critical for agriculture (eg fertilizer) and manufacturing. So expect them to start going pop, too. Or for sudden inflation explosions in all sorts of weird places around the economy."
It may be surprising to lots of people, but some (yourself included, and maybe even the likes of Michael Moore?) saw this possibility many years ago, e.g. prompted by the impact of Middle East oil crises (who remembers them now?).
E.g. the whole Western agribusiness sector disappears without "affordable" fertiliser, which is an unavoidable consequence of "expensive" gas, which in turn means those weirdo "organic" farmers suddenly become a whole lot more important. And there's more, much more.
As for what happens to the plastics industry... don't go there.