According to Nikon, upgrading your camera body might be a thing of the past. As a possible solution, one that addresses the rapidly changing technology in digital camera sensors, Nikon filed a patent application (in Japan) for an interchangeable sensor.
If I were having coffee-and-a-convo with a Nikon camera marketeer (and assuming language wasn't a problem) one of my first questions might be, "Is sensor technology the primary reason most photographers opt for a new camera body?"
I'm all for modular cameras. That's why, probably like you, I shoot with cameras designed to accommodate interchangeable lenses. I mean, who wants to shoot with fixed-lens cameras? Well, I suppose that depends on the camera and what your goals are shooting with it. Plus, as Chase Jarvis often reminds us, the best camera is the one that's with you. The pros and cons of fixed-lens cameras as well as Jarvis's advice aside, many of us appreciate being able to swap out one lens for another on our camera bodies. Now, leastwise at sometime in the future, Nikon says we'll be able to swap out sensors as well.
It's true the Big Two camera makers regularly release new camera bodies. They do it so often, in fact, that (IMO) many photographers, myself included, are somewhat cautious about buying a new camera body because of the likelihood that something better (i.e., better for me or anyone else considering purchasing a new camera body) might be just around the corner. That's probably one reason camera makers tend to be so secretive about new cameras on the horizon: They don't want to hurt sales of whatever they're currently touting as their must-have camera. What's coming next is in addition to the more important question, "Do I really need a new camera body?"
Maybe I'm reading too much into this interchangeable sensor stuff? Perhaps Nikon is simply protecting their R&D investments with their patent application rather than heralding the dawn of the age of interchangeable sensors?
I don't know about you but a camera's sensor, interchangeable or not, is only one factor when deciding to upgrade my camera body. Beyond full-frame-sensor versus cropped-frame-sensor decisions, there are other attributes of any latest-and-greatest camera body that come into play when trying to make such decisions. Things like video capabilities, processors, auto-focusing technology, burst modes and buffers and more.
I suppose we'll just have to wait and see where this goes.
The eye-candy at the top is Alexis. The schematic further below is the mechanical design for Nikon's interchangeable sensor technology. Personally, I'd rather examine Alexis' semi-naked form than Nikon's mechanical function. But maybe that's just me?