The long awaited Canon EF 24-70mm f/2.8L IS USM lens is still in testing by Canon, according to CR, there are two versions of the lens being developed, with only one coming to market. The announcement date for this new EF 24-70mm f/2.8L IS USM lens is unknown yet, maybe in late 2018.
Canon’s goal is to make the new IS version of the lens noticeably better optically than the current EF 24-70mm f/2.8L II USM lens and just adding IS to the 6 year old optical formula. The second goal of the lens has been weight, adding image stabilization adds weight and bulk to a lens. Nikon has already released the new AF-S VR 24-70mm f/2.8E ED lens, with add 170g to the old no VR lens.