I have only one question.. Why, why WHY?
Why do they even need to update the series? Cameras are not old, are not outdated, and it just seems stupid to release a new camera, just because of higher mp count. There's no real improvement. And there's a product for everyone. What do you miss? What kind of camera? Don't tell me, that anyone actually waits impatiently for a new rebel or xxD camera?
The only hole in canon's body lineup might be an affordable FF camera, but even so, 5dII is still selling well.
The Rebels are very capable cameras as anyone reading this site knows. We know that image quality comes first and we can easily know what are real and worthwhile upgrades. However, the Rebel line right up the T3i is primarily positioned as a consumer level / entry level DSLR. The bulk of the purchasers are buying their first DSLR, don't have any investment in lenses, and are comparing to all other brands. Most consumers don't want to buy "last year's model". I don't think there's much more than that to the annual refresh.