The 17-40 is supposed to be better on the wide end than the long end... while I would love an update i do have a few concerns...
A) this lens sharply increasing in price, 16-35 II, 70-200 2.8 II, 5dIII, etc...
B) like many newer updates, the lens becoming an 82mm rather than 77mm...
C) not really jiving over the variable aperture aspect of this lens... I would love a 2.8 option, but 2.8 on the wide end really isn't as much as a benefit as it is on the long end... But i dont know if it's even possible to have F4 on the 17 end and 2.8 for the 40 end... Kinda seems simpler to have a constant aperture, unless that will increase costs even more.