Canon has said in various EOS R and RF mount presentations that the RF mount is going to allow them to make some “world's first” type of lenses. We've already seen proof of this in the RF 28-70mm f/2L USM,
We're told that an RF 14-21mm f/1.4L USM is currently in advanced development and will likely be one of a couple of world's first lenses coming for the RF mount next year. After speaking with the source, we did confirm that there's more to this than just a patent published here back in November.
The same source said that a “crazy” prime lens will be coming for the RF mount next year, but that the focal length and speed were unknown at this time.