The supertelephotos are done for the moment from Canon. The last 12 months or so have been dedicated to updating and releasing new long lenses.
First words today that a 35 f/1.4L II is in the wild and being tested and critiqued by a select few photographers.
This is one of the oldest lenses that's been talked about for a replacement. It seems it may be a reality in the not so distant future.
There was no timetable given for release.
I will say this source has been right in the past about test lenses. The first mentions of the new supertelephotos came from this person.