I would have to imagine that a 70D upgrade would follow the path of the 60D, otherwise a 7D replacement would have to place it "closer" (minus FF) to the 5D3, which wouldn't make much sence, unless it came with a higher MP sensor than 18. I only say that because of the fact that the 7D was placed too closely to the 50D in terms of "features", Canon had to "downgrade" the 60D to make the 7D seem more attractive for buyers and users. (Don't get me wrong, I like the 60D, it's a very good camera)
The 7D is one heck of a camera. It is loaded with features and is still "high-tech" even from today's standards. They would have to replace it with something that would make even the 5D3 stand up and take notice. I mean heck, they took the best of the 5D2 and the best of the 7D to make the 5D3!
18MP cannot be where Canon levels the playing field, even if it is an "upgraded" sensor. If the new 7D2 is 18MP, I cannot imagine too many features added that would justity upgrading my current 7D. (Even if it shoots 10 FPS, or more and dual digic 5) Now, IF the 7D2 came with a 24, 30, or higher MP sensor (ASP-H, or ASP-C) sensor and shot 8 or 10 FPS, then I might consider it. Or if it came with a FF sensor, but I wouldn't trade it for a "lesser" MP sensor (14, 16, or otherwise) for the current 7's speed. Now that being said, if the 7D2 was 16MP FF and shot 10 FPS, then I may look into it. Video is not something I care about (or use) so I don't worry about what features or not it has with video.
My opinions are based on a possible "entry" level of a cheaper FF camera (that is also rumored to be 18MP) from Canon. They need bodies to fill different price ranges and features. A return of the 70D to the status it had before (I.E. 40D, 50D...) would make the placement of any 7D upgrade a difficult one for Canon.