If Canon are to keep the 1.62x crop alive then it needs a top end camera for pre-sumers to aspire to. Hence the need for a 7D.
Why? 7D must be quite marginal in sales numbers compared to the total 60D/600D/1100D/older crop models, and they did quite well for many years without a high end 1.6 crop model. IMO a 1.3 crop 7D Mk II (or whatever Canon would call it) would make a lot of sense, particulary if the go FF with the 1D Mk V. The sensor area of a 1.3 crop is not that much bigger, but would allow sligthly higher resolution and better high Iso performance. If Canon (or consumers) feel the gap between 60D and a 7D Mk II is to big then Canon could easlily make a 70D slightly better specced.
True, but there seems to be a relationship between the aspirational models with the more volume offerings. When the 1DIII's AF fiasco kicked off, there was a slump in canon sales. When the 1D4 was realeased, there was more confidence in the Canon brand as a whole (or at least that's what my local dealer was saying). Another example, BMW's premier cars are their M series, but these models are quite niche and low volume. BMW claim that they add brand perception to the whole range and are probably the most important cars in their range in both engineering and marketing terms.
This is why I think that it is important for Canon to have a top single digit (7D) 1.62x croped camera.
I think Canon will be forced to make the 1D series a unified full frame 10 fps camera because of Nikon's D3/D700 range, which will make the 1.33x cropped sensor a thing of the past....which is a pity becuase it's a great format.