I'm a little confused by the logic of announcing and waiting 5 months before releasing.
If they announce a new 1D on Tuesday, they will sell next to NO 1D stock between now and March, as people will wait.
The lower end Rebel etcs wouldn't have this problem as 1k for a body is a far more disposable amount than 5-8k.
People that will purchase a 1D will know the new one is coming, they will know.
Now if there is limited stock, then that again hurts Canon's sales. Why not announce CLOSER to the release date.
I'd understand if it was a NEW product, like the rumoured EF mount video camera, there is currently no predecessor on sale. So the wait builds the hype.
Helps people plan expenditure, helps avoid migration to a rival product, allows businesses who work on a financial year aligned to the calendar year to have it in the 2012 budget etc.
Take Apple. Everyone knows that once a year a new ipad and iphone is launched. The phone has moved to September but I think that's more to do with iOS 5 than the phone. But that aside, everyone who has a phone, Apple or not, knows when the next one will be available. Great for everyone from a planning perspective. It even helps Apple if I decide to skip a generation, as I know exactly when the next one will be released, so I am likely to stick with them...
Long winded way of saying, although it adds to frustration, most people I think would prefer to know what will be available as it allows them to make decisions. As has been mentioned elsewhere, it would be great if we knew all the Canon (1Dx/5Dx/3Dx) models at the same time, oh and also all the Nikon / Sony equivalents