I don't understand the comparison with cassette decks -- these are still made. Teac manufacture cassette decks, probably as nice as they think necessary today. But I don't doubt that they could make a higher-grade model if they wanted -- they do, after all, also manufacture USD 38,000 CD players with drives that look like
this. I am sure other of the old makers could make cassette decks, if there was an interest.
I imagine the abandonment of a new super 8 camera was more that it was going to be more expensive than they wanted rather than that they couldn't do it, but I don't have direct knowledge of the specific example you mention.
I think cost is the issue a lot of the time. Surely capabilities could be brought back or rediscovered if people thought it worthwhile. I think there is just a different mentality today, not usually for the better, about what products are valued and what people expect.
I saw a good quote once from someone about photomultiplier tube drum scanners: "Drum scanning is one of those old gems built in the days where engineers where given free reign to solve problems to the best of their abilities - that's why it's still unbeatable (quality wise) today." And it is true. The last drum scanners are from an era in publishing that has not been surpassed and represented a high point (for books and magazines that include photography) -- when publications were photography with transparency film, scanning with PMT drum scanners, and printing with offset lithography or gravure. People don't value that character and quality in the same way anymore.