We're told to expect a new 50mm lens, as well as a new non L 70-300 soon. These lenses may not be part of this Friday's announcements, but could be coming soon after.
There was no mention of the speed of the new 50mm and which in the lineup it would replace. I'd be surprised if it wasn't the 1.4 version that was getting the update, as that lens is over 30 years old. As for the 70-300mm, I would assume it would be a replacement for the non-L, non-DO 70-300 f/4-5.6 IS.