For those just joining us and trying to make sense of this non-trivial CR3 -- and are not furious right now -- we've been riffing on these possibilities:
1) Canon is fully '70-200'-ing their 24-70 lenses into a lineup of (eventually) four offerings.
2) This is tailored for video -- STM, parfocal, etc.
3) It will be very small / very light in comparison to prior 24-70 lenses.
4) This is a 'value L' in the vein of 17-40, 70-200 F/4 non-IS. Sub-$1000. Logically paired with the new 6D.
5) This will be legendarily sharp for the new uberpixel bodies we will get down the road.
6) This new 24-70 IS will replace the 24-105 IS and drive more people to buy pricey 70-200 lenses.
For the record, I really thought more people would be outright furious about this. I thought 50% of respondents would be out for blood. Good composure, team.