Canon Rumors reports of a tip that Canon is working on a new EF 70-200mm L lens. It would most likely be the aging EF 70-200mm f/4L IS USM model that would get the Mark II update.
No word on when the lens would be coming but sooner rather than later is likely. Canon has a habit of introducing professional lenses in the November-ish time frame, so that wouldn’t be a total shocker to see such a lens then.
Stay tuned.