Canon News has uncovered a patent for a lens that will surely be coming in the future from Canon. I have reported that a Canon RF 14-35mm f/4L IS USM was on the way. Perhaps the “14mm” was a type and it will in fact be 15mm at the wide end.
This patent also includes an optical formula that has a wide end of 16mm.
I suspect we're going to see this lens or something very similar announced in 2021.
[wpdatatable id=8 table_view=regular]