This really depends on what you mean by “long term”. Like the effects of EVs aren’t being felt now, or next year, pretty much at all. Right now consumption is still stable enough that producers can affect the price more than changing demand does.

In the medium term, significant demand drop will put downward pressure on pricing. The problem is that you can’t drop the price much lower before parts of the supply chain start having issues. There’s a lot less truly cheap oil than there used to be, extracting using oil rigs costs a lot for example. So expect it to fluctuate more, but not really cheaper.

And in the truly long term, several decades, it’ll start getting more expensive not just because of the economies of scale mentioned, but as certain current producers start running out of oil. Many Russian wells are already scraping the bottom. Saudi Arabia’a shallowest wells will run dry. So even with significant consumption, it’ll start costing a lot more just to produce a barrel.

Running out of oil isn’t going to be a thing though. Just higher extraction costs. In general oil doesn’t behave like a regular market though, the supply is just too elastic. Can always leave it in the ground.