We reported a couple of months ago that a new EF 70-200mm f/2.8L IS III was coming, and then we scaled that back to just a new EF 70-200mm was coming as we couldn't confirm the speed of the lens. Last week it was confirmed from outside sources that an EF 70-200mm f/4L IS II was indeed on the horizon.
After all of that, we still believe that a new EF 70-200mm f/2.8L IS III is still a possibility in 2018. We've again received a few mentions that such a lens is currently in testing and that it is scheduled to be announced in 2018.
We haven't confirmed this yet, but we hope to do so soon.