The long rumored Canon EF 100-400mm f/4.5-5.6L IS replacement will be announced in November, 2014. Now the demo versions have been in some photographers’ hands for field use.
Other detailed info are still unknown, please stay tuned for more info.
Post-purchase rebate: Save $200, Canon EF 100-400mm f/4.5-5.6L IS USM Telephoto Zoom Lens is available at Amazon for $1,499.
The new design resembles the EF 70-300 f/4-5.6L IS with a thin focus ring at the base, and a wider zoom ring near the front element. The aperture range for the lens will remain at f/4.5-5.6. Another mentioned feature is in the lens hood for the lens. It sounds like there will be a retractable opening near where a filter would be, so you could turn your circular polarize easily if you needed to.
Read more: Canon Rumors