AvTvM said:
there is no risk for Canon at all. Technically an excellent mount adapter...
It's not a mount adapter. There is nothing special or clever about that and it would not be worthy of mention as an EF solution.
My money is on a user-changeable mount. That is, the base camera has no mount at all; you install the mount you want to use, whether it's EF or otherwise. It would let them create a dovetail racetrack design that could be perfectly weather sealed and also appear visually seamless regardless of your mount choice.
Also, perhaps not a rapid-change, pins-and-springs mechanism, because these get loose over time, are less secure (especially with big lenses), and also result in additional tabs and latches that are not appealing. Perhaps one or two hex screws that you can replace with thumbscrews. I mean, how many people with 400mm+ lenses are annoyed that after time, they have play? How annoying would it be if
every lens were like that?