I like the current 24-70. It is so damn heavy though!! I hear the older 28-70L was/is an amazing piece of glass. On par with Nikon's 28-70. I have had two of the current 24-70's, but always traded or sold for other gear.
One was sold to furnish me with the 35L. I haven't looked back since. I do not believe we will see IS on the new 24-70. It would jack up the price to close to $2k. The market for that as a kit lens would be slim.