guysguysguys, everyone relax!
If this rumor does turn out to be true, it's gotta be a new kit lens for the 6D, most likely in response to Nikon's 24-85 VR. This would make it very light, easy to handle on a lighter FF body, and quite cheap.
I've played with the 24-85 and while I don't think the IQ passes muster, the size and weight are simply superb. It's about the same as my 85/1.8G and handles very very well on a D600, whereas the existing 24-70/2.8 would feel like a front-heavy hog.
Canon is not trying to sway any of you to give up your 24-70/2.8's in favor of this lens, they're just recognizing that the 24-105 isn't the ideal lens for the next generation of entry-level FF bodies. Assuming the IQ doesn't suffer as much as on Nikon's version (and the L designation implies it won't), it'll make a great addition to the Canon lineup. Take it for what it is, not as a replacement for any existing lens, and all will be well, I promise
+1 well said