If Canon can put IS in the excellent 17-55f/2.8 (and 24-105f/4) there is no reason they can't or shouldn't put it in a new 24-70f/2.8. If they don't it will be a huge marketing mistake. I sold my 24-70 because it didn't have IS and I was not really happy with the IQ. I kept the 24-105 because of the IS but I find (with my copies at least) the 17-55 IS is sharper.
The existing 24-70f/2.8 didn't need a focus limiter switch or a lock to prevent lens creep. Besides I am hoping a new 24-70f/2.8 will be internal focus (no barrel extension). So the if there is a second switch it must be for IS.
So here's to hoping there will be a 24-70 (or 105) f/2.8 IS, internal focus with center and corner IQ as good as the 70-200f/2.8 II IS
Correct. Why a 17-55 for the crop with IS and a 24-70 for FF without IS

doesn't make sense imho. If there's a 24-70 f/2.8 with IS coming out and internal focus, I'm ordering one right away