The rumor returns
A few new rumors for a mediun format camera coming from Canon. This talk has been around since about 2006 and probably prior to that as well.
The rumoured camera would somehow be compatible with EF lenses. The image circle in most EF lenses would be too small for a medium format sensor, so I'm not sure how this would be accomplished without running the camera in a “crop mode” and making new EF lenses for medium format.
I'm not overly confident on this one. I think something may have been lost in translation and by “medium format” they actually mean “medium format quality huge megapixel full frame camera”. The updated lenses spoken about would be to increase resolving power. I imagine all the recent lenses are already ready to go in that department.