Upload & Sell: On
The inclusion of IS in this lens would probably make it prohibitively wide. You can check out Roger's outstanding tear-down on the LensRental blog, to see how the lens has been redesigned from the ground up.
Since Canon was the pioneer in developing lens IS, and the fact they have just introduced a smaller aperture model of the same focal range, I think we can be assured that the concept was considered by its engineers and designers and excluded for practical reasons and there won't be a new model with "add-on" IS once the current model satisfies sales goals.
I own a Contax N 24-85 lens, and that thing is a monster -- nearly as wide (also 82mm filter) as it is long, and that is a "simple" design with AF added. I wouldn't want an L IS lens that matched that form factor.
Both Canon and Nikon examined the idea of IBIS early on. I don't recall the specifics, but both had reasons not to go that direction, and I don't think greed played a big part in the decision. Regardless, I doubt the complex new Hybrid IS would be possible at the sensor, not so accurately. Maybe someone can fill us in better on the historical reasoning for in-lens IS vs. IBIS.