Strange the new lens lost a stop of light at the long end over the previous AF-S lens. Surely, they'll justify that with sharpness and vignette, but my copy of the AF-S 18-140 is plenty sharp and dark corners are easily fixed in post. It'll be interesting to see a comparison between the two.
I still use DSLR's even after upgrading to the Z6, but my use has changed a little. The Z has become my daily shooter for shots between 14-300 in most lighting conditions. It's so much more portable and the user experience is much more enjoyable, IMO. My D7500 has been repurposed to a telephoto setup with a Sigma 150-600 almost permanently attached, and the D800 sits there waiting with either a Tamron 15-30 f2.8 or Tamron 85 f1.8 for the low light or portrait shots since I don't have a proper lens for the Z6 yet to cover that use.
I assume the DSLR crowd has very little to justify the jump if they're happy with their experience. At least, nothing like the promise of not having to develop film any longer. Until you use the mirrorless system and experience it first hand, its hard to explain whats better and why. I for one, didnt realize how painfully slow image transfers took until using the XQD. I also really enjoy the focus peaking and IBIS offered with the Z6. I would buy another Z before I bought another DSLR at this point, and that Zfc is mighty tempting!