I like the sound of the 16-35 f/4 with IS. A lot of my wide angle stuff is done while on vacation and without a tripod I'm usually cranking up the ISO quite high to maintain a decent amount of dof. I wouldn't be too bothered by the loss of 5mm on the long end if I did trade up my 17-40L for this anyway. The 24-105 has that covered.
I feel like there have been quite a few wide angle zoom rumors that something is finally going to emerge from it.
The EF-S one doesn't seem all that great an idea, so it has less range than the current 10-22mm plus it's slower with a varying aperture through 8mm of zoom range? That seems stupid. What's the plus here? Just Image stabilization?
APS-C users already have one stabilized lens with a 24mm equivalent fov in the form of the 15-85mm f/3.5 - 5.6 IS USM.
If I really needed an APS-C wide angle with stabilization wider than 24mm, I'd go with the EF-M 11-22 f/4-5.6 because if you don't have a tripod then chances are it's because you're moving around a lot or saving space.