I realize there is one huge problem with this idea and that is pricing, Something like Sigma's Bigma lenses, special the 300-800 Zoom would end being very expensive.
So I will start with the Tokina 11-16 2.8, then add Nano coating, SWM etc, and keep the cost below 1200 $, this is lost more than the Tokina, but remember it will look more like a baby 14-24 2.8FX lens
which lens do you think Nikon could copy or improve on
Pete