I believe camera makers have removed the sense of urgency for users to upgrade by creating products capable of very good to amazing image quality and advanced capability. Compared with 5 or 10 years ago, the average digital camera of today or even from 2-3 years ago (whether it is a $2,000 Canon or a $40,000 Phase One) is so capable that the urge to look for the "next great thing" is not near the level of the past. That doesn't keep us from wanting to see the next great thing, but whether we buy it or not is another matter. For many, while the desire may be there, the need is not as great. That is why camera sales in general, are not on the upswing. Want to reignite camera sales? Stop making such good ones.
The innovation and development breakthrough curve has flattened. What we see mostly with new products now are slight improvements / refinements of previous products. Not necessarily a bad thing.