In all probability they will keep making & selling the stuff to the millions of users of petrol and diesel cars still on the road after the ban on the sale of NEW cars comes into effect (if it does). New hybrids will continue to be sold for another 5 years after that. So there will still be a demand from a lot of users, not just motorcyclists.
I pass a vehicle recyclers on my way to & from work. Over the last 15 years that I have been regularly queing past the place, it has been apparent from the registration plates on the cars on the racks that the scrapping age is usually between 10 and 15 years from first registration, so it would be reasonable to expect that the last of the new diesel & petrol cars sold will be on the roads until somewhere between 2040 & 2045 at the earliest.
And there will be some applications where electric won't be practical , so there will still be a need for liquid fuel derived from oil. Given that most of the refined products that come from crude oil are not used as vehicle fuel (base materials for plastics, paints, lubricants, industrial graphite, lithium batteries ect.) going to electric vehicles will not see any appreciable reduction in oil production or refining.
A BP report I came across (while looking for the answer to a question) stated that known, proven, oil reserves in 2019 were nearly 50% greater than in 1999. So after 20 years of supplying an increasing amount of oil, there is a lot more now known to be available than there was before.
Oil isn't going away any time soon.