Being a longtime lover of the 200-400 f/4 / 180-400 f/4 models, I would love to see a 200-600 "S" with an eye to those past models. By making it a straight f5.6, it would require a larger front element and catapult the price to the $5000 (+) US level. While this model would suit my "wants," I do not see the 200-600 S being produced in the near future (or ever).
I suspect that the long delay for this lens is linked to the success of Sony's lens. While I have no direct insight into what is happening behind the "closed curtain," I would not be surprised if Nikon had partnered with Tamron to make the 200-600, and this design had an external zoom much like the Tamron/Sigma/ & Nikon 200-500 models. Sony's $2000 200-600 is more lens per dollar than the competitive non-OEM lenses in the FE mount, and the Sony version has been a gateway "drug" into the Sony system for wildlife & casual sport shooters. With the inevitable comparison that will be made and the "torching" Nikon experienced w/ the Z6/Z7, Nikon was forced to "take a mulligan" and redesign the lens.
My thoughts... the 200-600 will be a Nikon-Tamron collaboration like the 28-75 f2.8, it will have an internal zoom, but will not have the high-end coating or "best" super-ED glass. It will compete with Sony on price and performance, and we will have no fewer than 4 threads on BCG and FM comparing the Nikon to Sony... half of which will be closed by moderators trying to cool down the debate...
