The 85L ii is not "new", it's at least 6 years old now, I believe. I know it wasn't brand new when I rented it 4 years ago.
I have to take issue with it being sharp wide open. It's not remotely as sharp at f/1.2, as for example the 135L is at its wide open f/2 (not even in the center...and at the borders the 85L is pretty soft, and suffers from coma). Also, the 85L has a fairly high vignette anywhere near wide open aperture.
For anyone using it on a 1DX, I could better understand why they think it's extremely sharp wide open. Your pixels are fairly large on that camera. If your subjects are all in the center and the rest is defocused, you would never see the lens' faults at or close to wide open aperture.
I don't see anyone calling for weather sealing in a new version...seems like that would be good. Faster autofocus, would likely require a radically different design, would it not? I suppose a version 3 would need to autofocus faster, though. Just not sure how fast it could be.
As for IS...it would be nice, but IS isn't all that necessary at this focal length and aperture, unless you do a lot of landscape shots hand-held...or at least it seems so to me. If you're shooting portraits without strobes in available light...those people are still moving, even if only breathing. You still ideally need 1/160 if they are standing or sitting very still, or else even more shutter speed if you want to stop motion. Panning with IS and such a wide aperture, would be very interesting though, I have to admit. But like for "street photography", IS isn't all that necessary. It would also add weight to an already heavy "canon-ball" lens...
If I could afford (and justify owning) it I would buy the current version and be happy, though. Perhaps other lenses will come along that can really give it a run for its money optically, and be able to autofocus faster and as accurately (or more so). Not sure the Sigma 85 is up to the task from what I've read. As for the f/1.8 Canon...well, it's an f/1.8...but seems like an extreme bargain. But it is a much older still design.