I'm not so certain that Canon will introduce new sensor tech just for an 1.6 ...
You are basically right.
Still, the most practical thing to do when introducing new tech is to put it in smaller sensors first .
In fact, that's what Canon is doing already with the S100/S110/G15 sensor - which is made on new tech.
Eventually, this new tech will make it into DSLR sensors as well.
At that time, it would make the most sense if it's used for 1.6x sensors first.
Of course this is not guaranteed and Canon might have other plans.
To me, though, a 7DII with the same sensor as the 7D is kind of pointless.
introducing a new crop sensor in the 7D2 would follow the 7D tradition (although the 18MP 7D sensor was not really revolutionary or disruptive at the time; it represented incremental improvments with over-sold ISO performance imho). The 7D2 sensor will either be a distruptively new crop sensor (perhaps with 46mp influence) or it will be an incrmental improvement (with t4i heritage) in pretty colored wrapping, oversold to appear disruptive (like the 7D sensor was). If Canon builds and measures the 7D2 against the 7D, ("look, we listened and updated the 7D with better AF, 10fps...) then the upade will feel a lot like the 5D3: great anticipation, followed by some disapointment fueled by those who read numbers, followed by the realization that the camera is a very solid performer in the target venue, followed by arguments over whether or not one should upgrade, followed by a low DxO score.... etc. If Canon builds and measures the 7D2 against the market, then we will see some wahoo.