No they dont.
If you brought updated products out as soon as they were ready you might have a long spell when no new innovation came along.
Whilst Canon's range is selling at an expected rate they wont release a new product that will boost sales. They dont need to. It makes bad commercial sense
When the 5DII sales starts to drop off, then you will get news of the next model.
The sales might now drop of because people might now definitely wait for the upgrade with '99MPix' or whatever feature that will finally allow them to take the good pictures that the present ""sub-standard junk"" has prevented them doing.
Why are you so against progress and improvement, Fred Flintstone?
If you ran Canon, everyone would still be using 10D's because it's "good enough". It can take a good picture, sure it's more difficult, but as long as it's possible, why improve on or add anything to make a photographers life easier?
Or to open up more photographic opportunities that were previously constrained by the limit's of the 10D?