dmr said:
YES!
From the point of view of a camera manufacturer, why would they want to sell you a new sensor when they can sell you the whole camera?
They wouldn't.
I'm not suggesting that we will start building cameras from a box of components. But I am suggesting that it would make more financial sense to replace a sensor for $100 than to spend several hundred dollars buying a new model that's identical to your current camera except for that new sensor.
PC makers usually won't sell you a new CPU, either, Or a new drive, or video card, etc. Those are all made and sold by other vendors. Most of them sell to consumers and to the PC makers, as well.
All that is possible because PC's are built on an open architecture and according to a set of standards that define how all the parts will work together. While the internals of each component may be proprietary, if a vendor wants to succeed, he needs to ensure his product will work in any PC built on that architecture and heeding those standards.
This state of affairs exists because, twenty or more years ago, IBM failed in its attempt to replace its AT architecture with a closed proprietary system. They failed, primarily because Compaq, and then others, built better and cheaper AT clones using an open architecture and a BIOS with source code that was available for purchase. Vendors began selling the components such machines could use, and an industry was born. No one would dream of selling PC's that did not conform to the architecture. Even Apple, while retaining much of its proprietary nature, abandoned some of its own internal standards (IO and video in particular) and adopted standards developed on the PC side.
The equivalent in digital cameras would be, more or less, lenses that could be used on bodies across brands, interchangeable and replaceable sensors across brands, commercial availability of the source code for the software that drives a digital camera, and componentizing of cameras' internal circuitry so owners could upgrade it in a way that's analagous to swapping motherboards in a PC.
Camera makers do not now have an interest in seeing that happen because they profit by locking each customer into their proprietary system as much as possible.
BTW, the last PC I built cost me $900. Buying equivalent hardware ready-to-go would have cost me almost three times as much.