Canon has applied for a patent for a method of controlling the aperture as a user zooms through the range of the zoom lens. The idea is to control aberrations better throughout the entire zoom range and focus distances.
The patent provides embodiments of both at 16-35 2.8 and a 24-70 2.8 lens, both EF mount and both full frame.
With all patent applications, Canon is continuing to research future lenses, designs and systems, that may or may not end up in an actual product, or may be combined with other patents to form an actual patent. It's simply a good guide to see what Canon is actively researching at this time.
US Patent Application 20180180859