We have now confirmed from a couple of good sources that a full frame mirrorless camera is well into its development cycle, as the camera is being used by select Canon pro photographers. We reported back in January that a survey went out to some Explorers of Light about what they wanted to see in a “professional” mirrorless camera, and that dialogue has apparently continued.
While an announcement date is not yet set for the camera, and little is known about it specifications wise, I'm very confident we're going to see something announced before the end of Q1 in 2019.
One source said that Canon has been quite open about the product development with professionals because they want to be sure to “get it right”, and they don't want to fall into the trap of a first generation product not being great.
The biggest question I want answered is what will the native lens mount be? No one has provided any reliable information on that or any other specifications.
I wouldn't be surprised if we see a “development” announcement at Photokina if the camera itself isn't ready for production.
More to come…