Nikon will soon introduce the long rumored AF-S Nikkor 300/4 VR lens with Nano and fluorine coating. The new lens is expected to be very lightweight and will replace the current AF-S model ($1,369). Nikon has already filed at least two different patents for a 300mm f/4 lens - in 2012 and in 2013. Those are the rumored basic specifications:
Minimum focusing distance: 1.4m./55in. Filter size: 77mm Tripod collar will probably be sold s separately (just like with the Nikon RT-1 tripod mount ring for the 70-200mm f/4 lens)
Read more on NikonRumors.com: http://nikonrumors.com/2014/12/19/finally-nikon-rumored-to-announce-a-new-nikkor-af-s-300mm-f4-fl-vr-lens.aspx/#ixzz3MOpu4XBI