If the 7D MKII will have a crop sensor, I do not understand how the camera will have as good of high ISO performance as the full frame 5D MKIII.
The 5DIII is made on Canon's current CMOS manufacturing process - which is quite ancient and is well overdue for replacement.
The hope is that the 7DII sensor will be manufactured on a new manufacturing process.
If that's the case, the 7DII sensor will likely perform the same (or even better) than the 5DIII sensor.
Of course Canon will eventually make FF sensors on the new manufacturing process and FF will again pull ahead in performance.