Sure, but an FX 33MP sensor with a 600mm lens has the same 750mm FOV when cropped to the D500’s 21MP with a 500mm lens and we already know Nikon will replace the 200-500VR with a 200-600mm. As both the mirrorless camera and lens are lighter than the DSLR combo we get more lens for less weight.
Not sure if Nikon is still using Sony sensors in the Z6/7 cameras but if they do this sensor might end up in the Z6III, the a7IV is limited to 10 fps at 12bit lossy compressed RAW but the Z6III should easily trump that with the newer Expeed 7 processor and faster CFexpress B cards. Sony always seem to restrict their lower end cameras to protect the sales of their tier one cameras but Nikon usually provides the best camera they can make for a certain price range.
I agree that an FX 45MP at 10fps would even ideal for more range but I don’t think I am interested in a DX mirrorless camera for tele work as FX mirrorless cameras already have 94% coverage for the AF points and the EVF can fill the screen when DX crop is enabled which FX DSLR cameras can’t do but the D500 could which is why it is so well suited for long tele work.
If I was still invested in exotic Nikon glass I would go straight for the Z9 or wait for the ZIII cameras later this year but the 200-500VR is the only autofocus F mount lens left in the camera bag and am not particularly attached to it. So I’ve decided to build up a mirrorless lens portfolio of both Nikon Z and Sony FE lenses cherry-picking the lenses that suit my preferences the best and use them natively instead of crippling them with adapters. On the radar are the Sony 24/1.4 and 135/1.8 GM lenses which combine incredible sharpness with stunning boke, another candidate is the unique 14/1.8. For Nikon Zee I am currently mainly interested in the 100-400, 200-600 and the long primes but will lean back and let that unfold in the coming two years while using the Sony 200-600