Since all canons new lenses are the sharpest, I may invest in one. This what I think canon has in mind...
"rumored" canon 14-24 l 2.8 + 24-70 2.8 ii + 70-200 2.8 is ii - this is the pro setup.
Some f4 wide angle (ex. 12-24 f4) + 24-70 f4 is + canon 70-200 f4 is -enthusiast setup
-a new f4 wide angle
-maybe a new 70-200 f4 is ii
-maybe a 70-200 2.8 is iii
Maybe canon is using special glass, for the 24-105, they had to compromise on glass quality, I think since everyone wants a 24-70, they'll give a budget one, with good glass.
This could be a competitor for the tamron 24-70 vc, so people have to decide, tamron 2.8, or canon sharpness and build quality. With the Iso capabilities of canon dslrs, f4 won't be an issue, this is probably going to be launched with the 6d.