You're right that the 5D viewfinder is much larger than the 7D.
And in turn the 7D is probably bigger than the sad pentamirror finder of the T1i.
But nothing compares with the giant viewfinder of the medium format Mamiya RZ22! Playing with MF power, uh huh! o_o
The 1DIV may look like a new model but in fact is a mid-cycle facelift product.
As such, its lifespan will be short. The 1DIIn, for example, was on the market for less than 18 months.
The 1DIV is a more substantial facelift than the 1DIIn was but itâ€™s still a facelift.
Plausible, but consider the economic climate as well.
Also not sure where the Mark IV could make massive improvements, unless you want to turn it into a movie camera. It could use some more megapixels perhaps.
One of the biggest changes from the Mark II to the IIN was the back color LCD, changed from 2" to 2.5", a pretty noteworthy change. Right now it's standardized at 3" on most models. I'm sure some people would like to see a bigger screen still, and there may be some room before we run into problems like trying to make it a touchscreen to accommodate all the controls as well.
Also, even though the 1DIV is well specâ€™d, its 1.3x sensor format is a drag and is working against Canon at this time.
You dismiss the whole sports segment as "individual buyers?"
As for the AA filter and pixel-binning: like I said, these are low-level technical characteristics, not selling points.
No company will delay a flagship product for characteristics that many buyers have not heard of or donâ€™t understand.
Canon is a smart enough company - I would hope, else they are putting themselves in peril - not to ignore the AA filter. I assume you mean getting rid of the AA filter? Not smart. I'm sure there will be an AA filter developed specifically for the sensor used, as always), or fudging pixel-binning for video if other manufacturers can do it (considering how much data would need to be moved, while sensors continue to get denser in terms of megapixel, I don't see anybody catching up for the sake of pixel binning in video. Perhaps I'm not sure what you meant here, but AA filter and pixel binning perhaps aren't high on the list of photographer demands because they're relatively transparent to normal photographers and the demands of cranks uninvolved with camera development but who have concrete opinions about "best practice" haven't been reflected in Canon or Nikon camera development. If you want my opinion on what Canon really ought to do to make their cameras better, I would start with (for the low end) better quick selection of bracketing (have to dive into a menu on the T1i, though it's only a few seconds to do) and especially getting a better mirror lock up solution.