Knowing when a medium is dead

Was in a meeting yesterday with someone who also had the pleasure of making some CD-ROMs for museums years ago. I say pleasure as it was a lot of fun to run through archives, make films, pull documents, and take photos of rare artifacts but that was the problem. My colleague ran a small company then (has a really well known one now) and shared with me an epiphany he had at the time.  He told me that one day, in the middle of the big and only project they were creating for a large museum, he looked around the table at the 12 employees he had working on it that realized that not one of them had bought a CD-ROM in the past six months. It was then he said that he realized the medium was doomed. He was right.