New patent from Nikon (55-300 f:2.8-4)

Actually not too often.

Otherwise we could already buy a new 80-400 with AF-S, or a 100-400, or even a 200-500 f4-5.6.

All of them were patented by Nikon within the last few years. None of them is for sale today.

That 55-300 is just the next one in a long row of Nikon patents. We shouldn't hold our breath that it will ever materialise as a lens we can buy.