I see Nikon using Sony sensors, and Sony itself is using its new sensors in its new well-received bodies, and I read people discussing how the Canon sensors seem to be falling behind.
I wonder if Canon will reach a kind of "Apple Moment", like when Apple quit spending its R&D money trying to beat Intel on a component (CPU's) and started just using Intel chips like everyone else.
As was pointed out earlier, Apple never built their own chips. Also, Intel aren't the only company who manufactures x86 chips.
Apple made a number of smart business decisions and released several very successful products (imac, ipod, OS X) after Jobs took the helm in 98 (and well before they adopted the intel architecture in 2005)
One of the problems with having Canon drop sensors is that most of the companies who build sensors are either their competition, or companies who would like to become their competition.
Canon makes better lenses than Nikon, and could focus on staying ahead on that. They could/should take a page from the perfectionist Steve Jobs, and focus on addressing all the 1000 little niggling customer gripes and wishes about cameras, and making Canons just work better and smoother than Nikon (or Sony). Outclass the competition by thinking of everything, and including it; and by not withholding simple little crap in hardware and firmware that they could instead make standard in all their cameras for very little cost.
Providing nicer products is always a worthy goal, but the Apple way is not to push high end functionality down to low end models so that users of said low end models may aspire to have high end functionality made available at the low end price. Rather it would be to simplify and clean their product lineup by simply eliminating those "tweener" product lines so that these users are left to choose between (for example) the Rebel and the 5D.
Another lesson from Apple, by the way, is that they have never been leaders from a pure price to performance standpoint. Instead, they always lived or died by the idea that users would pay a premium (in some cases a fairly hefty premium) for a well crafted product.
Canon have an analogous though not identical approach -- their plan is essentially to build a compelling system. A good system is not just about sensor performance. It is a comprehensive product line, which includes professional grade support, bodies, lenses, and even printers. The only other manufacturer who can play in the same ballpark at present is Nikon.