I see the 6D is now $1649 from some suppliers. Even here is Australia, the global HQ of the Canon overpricing division, 6D's are $1800 (GST Excl). With the upcoming 7Dii and 70D, for the first time ever, we'll likely have APS-C bodies priced higher than FF bodies. Wow! This really complicates buying decisions. And not just across Canon's own range, but across the board.
And while I'm sure the 70D and 7Dii will have features to match their price and should appeal to many, given the image quality gains, you'd have to be very aware of your needs to forgo the 6D. The same with people looking at buying into another system with a higher end camera - eg Olympus OM-D, Panasonic GH3, Pentax K5ii. If your sole criteria isn't smaller and lighter, why would you bother?
And personally, while I've been considering a Fuji Xpro1 for fun, my logical side is telling me that it is inferior to the 6D in many ways and that I'd be very silly to buy one.
So after some crystal ball gazing, I've come to the following conclusion. The 70D will move up in specs to become the 7D replacement and will sell for a similar price to the 6D. At that price range, people will need to choose between speed, performance and better AF or the better image quality of the 6D.
But we won't see APS-C bodies selling for more than FF bodies. Instead, the 7D replacement will be a full frame camera selling in the $2000 - $2200 range. It will be a 6D with beefed up AF specs. Maybe the features of the 5Diii but with the 6D sensor to keep some differentiation (Or a 5Diii light if you want to think about it that way). This will become THE camera for the masses. And while it will cannibalize 5Diii sales, this will be more than compensated by the increased sales to those seeking the allure of a FF camera that ticks most boxes and those who would have chosen a 6D, but can spend a bit more.
Anyway, just wanting to put my prediction out there.