Nikon needs to make a constant f/4 tele

I have recently switched to FX (D600) and own the 16-35 f/4 and am in the process of purchasing the 24-120 f/4. I currently own the Tamron 70-300 VC but would definitely be interesting in purchasing an constant f/4 tele if Nikon were to make one. I know to keep the cost under $2000 it is doubtful they could make a 70-300 f/4 but perhaps 70-200 or 100-250 f/4? I feel like there is a lens missing from the lineup as the constant f/2.8 pro lineup has the "Trinity" but there is not something similar in the f/4 enthusiast lineup.