Nikon UK press release:
Nikon UK is pleased to announce the 50th anniversary of its legendary F-mount lens-mounting system, featured on the company’s SLR cameras and NIKKOR lenses. No other camera manufacturer has been able to sustain its original lens mount for such a long period of time – making Nikon’s SLR system the most consistent range for half a century.
The Nikon F-mount was first employed on Nikon’s earliest lens-interchangeable SLR camera, the Nikon F, released in June 1959. Nikon has consistently utilised the same mount without changing its basic structure, whilst other SLR camera manufacturers altered their lens mounts in response to changing technologies, such as autofocus compatibility and digitalisation.
One of the biggest advantages of lens-interchangeable SLR cameras is that users are able to choose from a larger selection of lenses. Maintaining the same basic structure of lens mount for a longer period means a broader, constantly growing array of compatible lenses, including the ability to use older lenses. For this reason, the lens mount is an important and symbolic element for both photography enthusiasts and professionals, who are able to benefit from ongoing use of their carefully selected collection of lenses.
It's pure speculation, but I can't imagine we'll see the Nikon F7 anytime soon, the F6 really doesn't need updating right now.