It seems that the Canon EF 100-400mm f/4.5-5.6L IS II lens is already officially announced - PDN already has their article online:
- Improved four stops image stabilization
- The original “push-pull” zoom has been redesigned to a rotating zoom (updated)
- Improved optical design: one Flourite and one Super UD lens element
- Newly developed Air Sphere Coating to minimize flaring and ghosting
- Minimum focusing distance: 3.2 feet
- Flourine coatings on the front and rear elements
- Weather resistant magnesium housing
- The lens will be priced at $2,199
Update: the post is now removed - I guess PDN published it prematurely. You can still access the cached version here.