Smartphones are replacing standalone cameras, but the analysis in the article is busted. Popular camera models are constantly being replaced with newer shinier models, so of course every model trends down a little while after release. It'd probably be a lot more enlightening to do the analysis grouping usage by family (e.g. Canon G11, G10, G9, etc) once and then doing an age analysis for each family.
As an avid smartphone user (have had several in the past couple years), the iPhone 4 camera is simply the first smartphone camera that takes really good pictures at a decent megapixel (5mp). Other smartphones are following, and the days of point & shoot cameras are numbered.