I may be naive given Canon's knack for p!$$ing off their most loyal customers, but I don't think the situation with the 7Diii is/will be the same as the 6Dii. The 7D is the high-end flagship crop sensor body, whereas the 6D is the entry level full frame body. While there is definitely some technological backtracking between the 6D and the 6Dii, a lot of the disappointment I read was from people who wanted the 6Dii to be a $2000 5D Mark V.
The more interesting differentiation, IMO, will be between the 7Diii and the 90D that is rumored to launch at about the same time. Canon will need to give 80D owners a compelling reason to upgrade to the 90D, but they will also need to make it clear that the 7Diii is the top of the line so it doesn't lose sales to the 90D.
I don't know how much attention Canon pays to competitors specs, but I was looking at Nikon's crop sensor flagship, the D500, a while back. Superficially, it's pretty impressive, as I mentioned in the other 7Diii thread: 10 FPS, 4K video, 153 AF points (99 cross type and 15 that support f/8), tilting touch screen, WiFi, Bluetooth, NFC... I hope Canon sets their sites on besting this!