Two f/4 Telephotos Coming
I'm told we can expect two new f/4 telephotos to be announced in January, 2013.
The first will be an EF 300 f/4L IS II, you can obviously expect better coatings, IS and a slightly lighter weight.
The second is said to be an EF 400 f/4L IS, no mention of it being a DO lens. With the price of the coming EF 200-400 f/4L IS 1.4x, mixed with the also expensive 400 f/4 DO IS, there is probably a big market for a 400 f/4 prime that is “affordable”.