With the just made announcement of the Z 28-75mm f2.8 lens, Nikon also announced the development of a Z 800mm f6.3 S VR PF lens. No information of its cost or weight, but based on difference between the F mount 500mm f4 and the 500mm f5.6 PF and then looking at the specs for the F mount 800mm f5.6, I would guess that this lens might weigh 5 or 5.5 lbs and cost $5000.
A great combo for wildlife photography that is lightweight and gives a great range of focal length, might be a Z9, 24-120 f4, 100-400 f4.5-6.3 (which when used with 1.4X TC goes to 560mm f8) and 800mm f6.3 PF (with 1.4X TC goes to 1120mm at f9.5). Z9 should have no problem with AF at f9.5.
I would then be tempted to trade in my beloved but heavy F mount 600mm f4 - I'm getting too old to be carrying it around. And then rely on Topaz DeNoise AI or similar software to handle the increased noise when shooting in low light with higher f stops.
A great combo for wildlife photography that is lightweight and gives a great range of focal length, might be a Z9, 24-120 f4, 100-400 f4.5-6.3 (which when used with 1.4X TC goes to 560mm f8) and 800mm f6.3 PF (with 1.4X TC goes to 1120mm at f9.5). Z9 should have no problem with AF at f9.5.
I would then be tempted to trade in my beloved but heavy F mount 600mm f4 - I'm getting too old to be carrying it around. And then rely on Topaz DeNoise AI or similar software to handle the increased noise when shooting in low light with higher f stops.