Canon slotted the 60D perfectly in-between the Rebels and the 7D.
Yet, the 60D is perceived as a super-Rebel and Canon is forced to sell it at Rebel prices.
To change that, Canon will likely spec the 70D better ... which will make it very close (identical?) to the 7D.
So ... you're saying that Canon will push the xxD line back up to around where it was was BEFORE they introduced the 60D?
The 60D was deliverately pushed down in the lineup to make a bigger difference between the 7D and the xxD line (compare the bodies of 50D with the 60D if you're in doubt), so I would doubt that Canon would reinstate the xxD line to where it was before. Personally, I consider a 7D2 (or whatever they'll end up calling it) to be more likely.
But we can definitely agree that there's a hole between the (Super) Rebels and the 5D's at the moment. As I see it, it is obvious that Canon will fill that hole with "something" - and right now we're calling that "something" 7D2. I don't see Canon pushing a "70D" upwards.
I have a 50D and would be looking to buy such a 7D2 body - I don't have the urge to pay for a FF sensor - an APS-C sensor is just fine, thank you. Since I shoot a lot of motorcycle track riding/racing, an upgraded 7D along the lines that has been suggested in this thread, would be close to perfect for me: I'm looking for a better AF system than I have now, better high-ISO performance and better IQ (neither the 50D nor the 7D images looks really sharp and crisp to me). No Mpix monster either, please - I have enough "bit-weights" on my hard drive(s). I rarely use full-auto, so the actual fps doesn't matter that much for me (8fps is fine), but the 7D feels much more 'snappy' than my 50D.
It's quite unlikely, though, that Canon will make a special sensor just for the 7DII.
More likely the 7D line will just be discontinued.
Depends on what you mean by "a special sensor". If you're thinking an APS-H type sensor, I agree.
But I would be very surprised if they didn't make a new sensor at all for a 7D2.