Canon won't be able to charge too much premium for the 7DII if it has the same sensor as the 70D - regardless of AF.
They collected quite a premium on the 5DIII over the 5DII when the most significant upgrade was the AF. My guess is that the new 7D will end up with the 5DIII style AF. That would actually be pretty nice on an APS-C body.
With the 5DIII it's different: it's a real pro body, second best in the lineup after the 1DX.
The alternatives are a hamstrung 6D or a crop camera with inferior image quality.
This makes it easy for Canon to charge a hefty premium for the 5DIII - solely based on features.
Not so for the 7DII, which will have a cheaper but still very well spec'd and capable competitor in the face of the 70D.