Digital cameras lived as a complement to cameraphones for a couple years, then not so much. They are an example of how technology moves from “used-with” to “used-instead-of”.
Digital Camera Decline is an example of Gradually, then Suddenly.
Some people claim that smart phones and Instagram killed Kodak, John Markoff says that isn’t so. See The Kodak Jobs Myth
Cable TV was also initially a complement to broadcast TV, a way to boost the quality of reception. See Cable as Community Antenna
Source: Digital Camera Decline