We have an awesome crop camera in the 7D, is it too much to ask for awesome glass to go with it? If Canon were to finally come out with an EF-S "L" lens, what do you wish it would be? Try to make it plausible, and technically possible. Posting something silly like 4-800mm f/0.95 DO IS USM ABCDEFG is even more useless than any post of this type already inherently is.
The lens that would make me weak in the knees, tingly all over, and trip over my tongue while I run to the store...
EF-S 14-70mm f/2.8L H-IS USM
Slightly more useful focal range than the current 17-55/2.8, 3-4 stop hybrid IS, weather sealing (no more sucking up dust while zooming). I honestly don't think I'm asking for too much. Am I?
I think you might be asking for a leeeeetle too much.
1st, it would make the 24-70 which is NOT a light lens by anyone's standards feel like a paperweight, that's a ton of glass you're asking for.
2nd, L lenses are strictly EF mount, they can be used on any body from a Rebel to a 1Ds. Making it EF-S means it won't mount up to the 5D or either of the 1D flagships, why build such a monster lens if the pros who would be more likely to buy it can't use it?
And finally, you will not get a constant 2.8, 5x, weather sealed, 4-stop IS USM L zoom for less than $2k. Hell, I don't think Canon would sell that lens for any less than $4K.
It would be a killer lens but it just ain't gonna happen.........