I agree , I really thought the 400mm 5.6 would be next .
This lens won't show up now for at least next few years.
If Canon might loose one sale of the new 500 f4, they won't risk it.
Look at 60D - why didn't they include the focus micro-adjustment?
Would it make this camera more expensive? No, it's only one software option,
would add $0 to the camera price.
But they couldn't risk any 7D sale lost. They wanted to have the extra option between
Rebel and 7D, but they didn't want to loose any sale of the more expensive camera...
All they do is trying to make as much money as they can still make.
If they release a new small mirrorless system, it would kill a lot of D-SLR profit.
So they will wait as long as they possibly can. Any D-SLR profit now is free,
no R&D spendings anymore, nothing.
The answer to all that is pretty simple - stop buying all those new toys just because
they are new. If they see the money lost, they will do something.