I have the DX 18-140mm VR lens (that was the high-end kit lens option). It's surprisingly good, and it's clearly going to be smaller and lighter than could be achieved with a full-frame equivalent. You could argue that noone will miss this lens, because they should have got it with their camera.

Long lenses, I can use any FX lens, without any problems. The only thing that I would really miss if DX lenses disappear is a super-wide lens, because no FX lens is going to be super-wide on my DX camera body.

I was oversimplifying a bit.

I should say “most will not miss these DX lenses as Nikon moves to Z-mount APS-C cameras, which have the potential for both better optical quality and smaller size.”

To whit: https://www.zsystemuser.com/z-mount-lenses/nikkor-lenses/nik... — it’s the cheap pack-in kit lens, but the optics are off the charts relative to its size and price.

I like the DX 18-140 a lot. Still gets nice pictures, even when paired with a D200. I do get the slow shift to mirror less systems. And it was to be expected that the DX format gets axed first.

What is nice, so, is that the Z6 and 7 are getting cheap enough to become an option compared to mid to high end FX systems. Especially if you would start from scratch anyway. And the option of using used, but solid, F mount lenses on a mirror less camera has some charm so.

I imagine there is enough inventory in the channel to fulfil orders for the next N months.

Also am curious to whether there's an improvement in telephotos with mirrorless. The big selling point for rangefinders over the years has been the image quality bonus with compact lenses.

I'm not aware of a physical property that would cause mirrorless to improve image quality.

Mirrorless does allow a shallower flange distance, which allows you to create more compact/lighter lenses, but this is more beneficial with already small lens types (e.g. primes/compact zooms) rather than telephoto lenses.

That being said mirrorless lenses likely will be better, but not due to mirrorless Vs. DSLR distinction but because the mirrorless version will be their most up-to-date optical technology.

I think the biggest differentiator here won't be IQ, it will be the electronic viewfinder (w/focus peaking, zebra stripes, histograms, preview of art modes, more accurate preview of the photo, etc).

Having a shallower flange distance theoretically allows for an improvement in image quality. The amount of air between the lens and sensor causes a small amount of diffraction since air isn't perfectly clear. The combination of diffraction caused by that gap and a super narrow depth of field is why most camera mounts don't have a lens wider than ~f/1.2. I can't imagine it would make much of a difference at narrower apertures, but there is at least a basis for having better image quality on a mirrorless sensor.

But I totally agree with you, the advances in optical technology and the EVFs make a much bigger difference.

Diffraction is a property of light, it still happens in vacuum. The air turbulence can cause image degradation, but it requires many meters of it to become noticeable and is a complete non issue within tens of millimeters inside the camera.

The main reason for the improvements in quality - closer (and for some - larger as well) mount allows more freedom for lens designs, leading to previously impossible approaches. Another change - with photographer never seeing a direct image from lens (only a processed one via EVF or back LCD) - the abberations that can be easily corrected in post can remain less corrected by lens design, allowing better correction of other parameters within the same constraints.

The shallower flange distance provides lens designers with more leeway, so that the extra space and weight available can be utilized to make faster lenses, or more complex and corrective lenses compared to an SLR lens of the same focal length and speed. My Contax rangefinders, for example, had very compact lenses of incredible quality (e.g. 45mm f2) but nothing especially exotic. Leica on the other hand brought out various Noctilux models (e.g. 50mm f1) that was superior optically to its equivalent Canon and half the weight. And probably five times the price.

The advantage was most likely down to little compromise on design and cost, but it was there. Current mirrorless lenses appear to going the Leica way of both incredible optical performance and cost, no longer constrained by the mount.

I mean, you've as much as said this, I just thought to add some anecdata. A key driver of these improvements have of course been the ever-increasing resolving power of the sensors needing ever-better lenses. The Zeiss 45mm is my favourite lens ever, but I would not pretend it has the resolving power of a lens made in the last four years. There is of course, more to a lens than resolution, as the Zeiss 50mm C-Sonnar which I cannot part with proves...

I am very impressed with modern mirrorless cameras and lenses, but it is unlikely I will personally be able to dive in, on the grounds of cost.

I don't know much about what these products do, but I do know there are massive inventory shortage problems in the camera market as a whole.