I think one of the problems with Canon's DSLR lineup is that they have too many models on the market. It is not really economical to support future development of all of them.
I believe that that is one of Canon's biggest problems right now. I also believe that Canon, for years, have continued to set the bar of performance for DSLR's.
1) The 5D was the first "compact" full frame DSLR, it was in a class all on it's own. (Nikon didn't follow until about 3 years later with the D700)
2) Even though the Nikon D90 was first, Canon raised the bar by putting video into the 5D2, a camera that was ahead of it's time and far superior to the D90 (at twice the price) in many ways. To this day, it's a very popular camera.
3) The 7D was loaded with features and speed and showed what a high performance crop body could do. A test bed for a lot of the technology that is found in today's Canon bodies.
4) The 5D3 integrated affordable speed and fantastic full frame image quality into a compact DSLR body (compared to dual-grip bodies), not to mention many other great features.
5) The 1DX stands king of speed and image quality. It was smart for Canon to blend the 1Ds and 1D lines in favor of this new powerhouse and sales proves it.
I think a lot of people got used to Canon always leading the way and lately it seems like the semi-professional APS-C segment (I.E. 7D line) has been largely ignored. The 70D is a very nice camera, but it's no "7D". Maybe it's on par with the 7D but certainly not "class-leading".
Something else to consider that didn't necessary exist a few years ago is now we have a market flooded with tons of awesome used camera equipment for dirt cheap. I mean, the 40D was $1600 new and now you can get bodies for $250-$300. It's a powerhouse of a camera and still takes fantastic images. It's getting harder and harder for the companies to "impress" the people with REAL usable features. There will always be the useless features that look good on paper but I'm not too concerned with those. Not to mention the fact that DSLR's are still expensive and not everyone has a grand laying around to just buy new equipment each time a new body comes out.
One more thing is that not everyone shoots video, I don't. My 7D takes video and I have never taken a video with it. I am a still shooter so I don't look at DSLR's from a video point of view and I am sure there are plenty of people out there who feel the same way as I do. I think Canon is starting to forget that people still take still photos. Seems like more attention is being placed on video features than photography features. From a still photography point of view, just about all of the APS-C bodies from Canon over the past 3-4 years have been pretty much the same, just my opinion...
I always figured that when they released the T5i (at 5fps) they would integrate the xD line into the xxD line. Well, the 70D came out and I suppose with 2 entry level cameras under the Rebel line, it is still possible, but I thought they would get rid of the xxD in favor of a 7D replacement rather than the other way around. The fact that Canon has been mum on any news regarding any kind of 7D replacement adding to the V2.0 firmware update unlocking many new cool features to the 7D makes me wonder if they will even go down that road. Again, Nikon does not have a "7D" and they may feel the D7100 is sufficient enough competition to the 7D that they don't need to make a higher performance crop sensor body. The 70D is pretty close to the 7D in terms of features that I believe that a lot of people will buy the 70D on the fact alone that it is simply a newer camera body than the 7D.