I expect that there will be either a EF-S 15-55 2.8 IS, or 15-50 2.8 IS to replace the current 17-55 which is getting a bit long in the tooth now.
That would be a quite logical step from Canon if they'd like to provide the same range for EF-S users as the EF 24-70 f/2.8 for FF.
However going towards the wide angle may not be the perfect lens for some (including me). The wide end has quite some perspective distortion that let alone artistic photos have more cons as pros.
Also variable aperture zooms are the fastest at the wide end (though e.g. the 15-85 is f/3.5 only between 15-17 and the f/4 range is also quite short) so that can be covered quite easily e.g. with the 15-85.
I'm actually happy that 17-85 was extended to 15-85 as if I don't have any other choice I can still use the wide end (though I'd rarely go less than 20-22).
The shallow DOF (that comes with the big aperture) combined with the wide angle can be almost as tricky to use as a tilt-shift without its advantages.
That's why I'd consider a decent fast zoom (can be also EF-S) in the range of 24-70 or 35-70 or around that as perfect candidate for EF-S "L".
That combined with the excellent EF-S 15-85 walkaround (the other EF-S "L" candidate)+ one of the new EF 70-200 variants (IS f/4 or f/2.8 II; zoom doesn't need to be EF-S) would very well satisfy most non-artistic needs.