Camera sales were on a roughly 10-year tidal wave as the digital revolution was born, developed, and matured. Now that we've hit the "good enough" level with everything from smartphones to compacts, to bridge cameras, to d-slr's to medium format digital, there's lot LESS incentive to upgrade to a new camera to get a 10 to 15 percent improvement in image quality or another "10" value added to the new body's number badge. The photo industry tend to do this behavior every decade and a half or maybe a bit longer--the industry leaders are ALWAYS on the lookout for the next, big, new thing. At one time, that was the Polaroid camera. Then it was the 35mm manual focus SLR. Then it was the compact zoom camera or the 35/70 dual-lens compact camera; then it was the autofocusing 35mm SLR with automatic film advance....and then digital was launched.
During each of these boom cycles, MANY people re-bought their cameras because they were convinced that there was a real benefit to getting a new camera. That is the way the photo retail business works...but now, the smartphone has combined small computer, video player, telephone, e-mail app, messenger app, video camera, and still photo camera, alllllllllll in to one, single,light, easy to carry device. This is the first real encroachment of another technology into the domain of the camera and video camera. Camera sales are declining, because there's less and less need to buy the next, big, new thing....people ALREADY own this new thing, by the hundreds of millions, world-wide.