Is Nikon neglecting the DX format?

I don't see the lack of DX-format primes being an indicator of abandonment. I believe the white shirts at Nikon are far more in tune with the market than us mere mortals. If they see an opportunity in the market, then I would think that they'd fill it. Take a look at what Sigma, Tamron, Tokina, and Samyang have for the prime DX market - it's pretty small. Sigma has a DX 35 f/1.4, and I'm sure that if they experienced large sales, then Nikon would certainly want to jump on the bandwagon too. My guess is that Nikon and the 3rd-party lens makers see the average DX shooter as someone who wouldn't want a prime lens in the first place. Primes, specifically f/1.4 lenses, are most often used by enthusiasts and pros alike. The average joe with a D3xxx is almost never going to go out and get a f/1.4 lens. Or, at least that's my guess as to why they offer the lenses that they do.

Let's face it, the only reason people go with DX format cameras is because they can't afford or can't justify the cost of an FX body. If the prices were the same, then I don't believe anyone (except for wildlife shooters perhaps) would ever buy a Nikon DX body. Now that the prices have come down, the choice to go FF is becoming easier, and at some point it's going to be a no-brainer to go FX and not even consider DX bodies.

I don't think they are neglecting the DX format. About 1/3 of their lenses are DX format specific, and all their FX format lenses fit and work on the APS-C cameras, though some may not autofocus.

As your second update shows, you know they continue to upgrade their DX format cameras on a regular basis. Their 3 lines, D3xxx, D5xxx, and D7xxx, seem to cover the market quite well. What else would you have them do?

If you want better lenses for your DX camera, get FX lenses. If you want wider lenses, get from other brands. The fact that Nikon allows third-party lens makers to use their mount on those lenses is enough support already for the DX market.

APS-C never was endangered. It's cheap. It's the largest dSLR market ever since it was introduced. Producing superb image quality depends mostly on your skill. It doesn't matter what camera you use, FX, DX, mirrorless, or whatever as long as you feel it is the right tool for you.

Not really.

Nikon's removal of body motors from their budget bodies means that - unlike Sony and Pentax - you have to check whether a lens has a motor or not, but there are more than enough motorised lenses around.

Canon have a similar problem, in that their cropped-sensor lenses don't fit their full-frame models, but it doesn't hurt their sales either.

It's funny that any Pentax or Sony A/Minolta AF lens gives full functionality with any DSLR/SLT body, and Sony provide sensors to Nikon, but people are so thick, they only look at two manufacturers.