Canon has filed three super telephoto prime lens patents in Japan, they are RF 400mm f/2.8L IS USM Lens, RF 500mm f/4L IS USM Lens, and RF 600mm f/4L IS USM Lens.
These super telephoto prime lenses are expected to be announced in 2020 to 2021. Along with these super telephoto prime lenses, Canon may also introduce the EOS R Pro mirrorless camera for sports/wildlife photographers.
via:so-net