It's also possible that Canon will make its mirrorless camera larger-than-FF, AKA "medium format," to join the Hasselblad and Fuji medium-format mirrorless models...and prevent those brands from making inroads from that front.
Rumors have circulated regularly of a Canon medium-format camera for many decades now. The first one I heard about was in the mid-to-later 1980s, when it would have been a film camera. And no doubt Canon has done due diligence over the years with mock-ups and prototypes; the details would mostly be proprietary, though, so full disclosure is impossible.
Another unsubstantiated rumor...an industry legend, who is gone now, once told me that his friends at Canon privately confessed to him that Canon was only afraid of one company, and it was "not Nikon, and not Leica." That company was Fuji. That was surprising at the time, because that was way back when Fuji essentially just dabbled in the camera market. As we all know, Fuji isn't dabbling any more. So that might support the idea of a FF+ sensor mirrorless camera from Canon, as it would answer Fuji. Japanese companies traditionally pay the most attention to what their Japanese competitors are doing...and not what we consider their Japanese competitors, but what they consider their Japanese competitors.