An 800mm lens feels too marginal to be this years focus point from the camera division. Especially since it's "just optics".
They want something that makes the investors impressed and willing to continue to back the Canon stock. So it has to be high-tech. And must be possible to present in a way that it implies Canon as not just a dominant player but preferably market leader in that niche.
Every year in the annual report, they pick one or more products from each division and write about to show what a marvelous company Canon is, and to indicate that Canon will stay a super player in their market areas.
Most likely a video camera. Because they've had nothing special for stills for years.
I'd welcome an even-better large-format printer, though. Something with better gamut than the Epsons, or photo-quality uncoated paper printing, or something like that.
Seriously, Canon still makes fantastic cameras but the times they are a changing and Canon seems as if it's struggleing to keep up. The difference between my 5DII and my work D800 is very noticable, not enough for me to switch at the moment, but if Canon continues to languish and the D800 replacement comes out improved, that decision will be made harder.
