Canon is allegedly working on a full frame mirrorless camera. And the rumors said some sort of early prototype already existed although it never came out of Canon’s labs. Maybe it is still undergoing lab tests and development. And this Canon full frame mirrorless camera is expected to feature 4K video recording.
According to the report from CanonRumors, the upcoming Canon full frame mirrorless camera will be EF mount and it is expected to be announced at the end of 2017 at the earliest. And it is highly likely that Canon will announce a full frame fixed lens mirrorless camera first before we see an ILC full frame mirrorless.