No need to get nasty.....WiFi & GPS will be internal. We all figured this one.
This means it will not be a completely mag-alloy body so that they can put an antenna in the body somewhere to receive RF signals.
If you look at the body of a 1DX you will see that it is more full of holes than a swiss cheese. Lots of places for RF to penetrate inside, but it is even easier to put the antenna on the outside of the metal frame and cover it with rubber or plastic.
Why don't you put a metal box with the same number of holes in it as the 1DX around the antenna of your WiFi box at home and see what that does for your WiFi use.
I mentioned that the metal body is more full of holes than a swiss cheese because it is not a sealed box. there are dozens of holes through it so adding another one will have no effect on sealing. There will be a lot of RF leakage through those holes. Some are tiny, some are big enough to slide a battery through, and there is even one hole as big as a lens mount. There will be lots of RF leakage.
I also said that it would be easier to mount the antenna outside. There are lots of good places, like on the front of the body, like on top of the viewfinder, like around the LCD, like on the camera bottom, or even on the sides.