Canon is rumored to announce the development of a new 800mm f/5.6L IS USM lens sometime by the end of 2014.
As being said in the previous rumors Canon is working on the next-generation 800mm f/5.6L lens and the telephoto lens is scheduled to be announced in late 2014.
Canon To Announce EF 800mm f/5.6L IS USM II Lens Development in Late 2014
The new Canon 800mm f/5.6L IS USM II lens will be lighter than its predecessor. The new lens will also feature an improved autofocus system, better image stabilization technology, and enhanced image quality.
The new Canon EF 800mm f/5.6L IS II lens will replace current EF 800mm f/5.6L IS USM. The development of a successor is rumored to be announced sometime by the end of 2014.