I could be wrong. Can you cite where Canon said that Wifi was the reason for no flash on the 6D?
I don't have a source either, but I suspect that gps is more of a reason than wifi because the chip needs to look up for obvious reasons ... for the same reason the 70d seems to have a flash, but lacks gps.
GPS does not
need to "look up". If it did, then GPS would stop working when you turned the camera to take a photo in portrait orientation, and a metal-backed phone would not be able to support GPS at all, because it would not be able to see the GPS signals coming from any satellites that aren't behind you. Radio signals just don't work that way unless you're using a directional antenna.
While I understand the convenience of a built in GPS, personally I wouldn't let that be a deal breaker compared to all of the other amazing features the camera seems to offer; you have options at least. The GPS accessory, or an external 3rd party GPS that you leave in your bag and sync up later in Lightroom.
The 3rd party GPS devices are A. one extra device to forget to turn on, B. one extra set of batteries to forget to charge, and C. an extra step at the end. The Canon version is very clumsy to use if you're using an external flash, though I guess it also supports logging mode, in which case it becomes an extra device to forget to turn on, extra batteries to forget to charge, and an extra step at the end.... Either way, having experienced the way cameras should behave with my iPhone, I'm finding myself more and more disappointed in a company like Canon being seemingly unable to do something so simple as in-body GPS.
Yes, it would be great if that extra step wasn't needed, but I doubt you'll see GPS in a 7DmkII - if Canon wants to maintain the ruggedness and weather sealing of the original 7D, I doubt you'll see GPS or wifi given the need for the top plastic plate....
I can think of no technical reason why Canon could not mount its GPS and Wi-Fi antennas inside the display bezel like Apple does with the Wi-Fi antennas on the MacBook Pro. It's not like the screen will ever be made of metal. And if they find that the signal isn't good enough for some reason, there are lots of interesting tricks they could do to get around it, like adding a couple of tiny bands of metal somewhere on the front, separated by rubber seals from the rest of the body.