I suppose the major issue would be...........even if Nikon is really undergoing such a project, it would not be in CONTAX G mount..........
As major camera manufacturers would gain profit mainly from the sale of lenses instead of bodies. This is clearly the strategy of Sony (with relatively cheap bodies but rather expensive lenses...........)
That is also why I suppose an S6 Pro should not be that far away. Even if Nikon would lose profit from the sale of one Nikon D700 body, it can be compensated from the sales of more than one Nikkor lenses! (Only would be an exception for ZF fans like us.......
)