I'm talking about the specific observations made by Clayton Christensen about how some innovation "helps create a new market
... and eventually goes on to disrupt an existing market ... displacing an earlier technology there" [wiki disruptive technology]. It's really classic and it's not about adapting or becoming irrelevant. Companies find it almost impossible to disrupt themselves because usually when the innovation comes along it's not capable of serving an existing company's customers. Over time, with a trajectory of improvement, the innovation meets mainstream needs and displaces the incumbent (vacuum tubes/transistors, mainframes/minicomputers, chemical photography/digital photography and so on). Clayton's book The Innovator's Dilemma is probably the best read on this topic.