My view is we did not need this lens to be around. Canon DSLR users like me, would appreciate if they come out with a 18-50mm F2.8 whether is for 35mm or digital doesn't matters. 1.6 X would give use something like 28-80mm angle of view.
I would rather buy a sigma 24-70 f2.8 if I need this range. I can use that for my 35mm as well. So I think something is truely amazing about the Sigma for them to come out a duplicate but less useful lens.
IMHO, anything like a 18-50mm F2.8 to replace their 17-35mm f2.8-4 would secure them as leader in this third party market for digital users immediately!