Nikon Rumors claims to have info that Nikon will announce a replacement for the AF-S Nikkor 300mm f/4 VR lens with Nano and Flourine coatings very soon.
The new 300mm f/4 VR lens is expected to be lighter than the current lens. It will feature a minimum focusing distance of 1.4m/55″ and a 77mm filter size.
Stay tuned.