Science-Fiction is full of examples of stillborn media, and so are lots of political and economic proposals. Here is a small list of stillborn media I just made. I'm sure there are lots more. Small radio transmitters inside people's bodies, so they can be tracked down. AI generated art.
Real multimedia shows.
That is, shows that employ other senses than hearing and seeing, such as smell, touch, or taste. It is possible to introduce, for example, plot-related smells in a movie theater, but no one seems very interested in doing that.