An RF mount cinema camera of some kind is likely an inevitable evolution in Canon’s ecosystem when such a camera will appear is unknown at this time. I imagine the lens lineup needs to be a bit bigger before we see this sort of camera come to market.
Canon News has uncovered a patent that shows such a camera in great detail. The patent itself is related to reducing the size of the forced air cooling smaller and more efficient, therefore reducing the size of the camera.
As you’ll see below, the technical drawings for this camera are quite detailed. It shows a very modular camera design, it looks to be about the size of the XC series of cameras. We believe the Cinema EOS lineup will be moving to more modular designs as we’ve seen in the recent EOS C500 Mark II.