Maybe it’s just me but about the only things the GFX line and the Z7 have in common is the resolution.
The Z7 would likely be “better” in more varied situations with more unpredictable conditions comparatively (especially if one has an extensive Nikon F collection). I think the obvious areas where the GFX would potentially outshine the Z7 is in landscape and portraits with having a larger sensor to give more natural tonality/the lenses across the board to match the sensor. Nikon simply doesn’t have the lens range yet but is set to within the next 2 years or so. I don’t really see them as an either/or decision but rather a GFX and a (insert camera of choice here) decision. For more consistent color a Fuji X makes a lot of sense (I explored this option for myself) but pretty much anything would work in reality. For a lot of reasons if you can only have or only want a single system FF 35mm makes a lot of sense (and paired with a Micro 4/3 for happy snaps/travel makes sense). For pros or people with specific needs a Fuji X and Fuji G makes a ton of sense.
....yes the Z7 would absolute be the the most sensible solution, and I have looked forward to fulfill this dream of a solid "familiar" decision.
But I have used the Hasselblad SWC for several years, several years ago, and its the only old topgear camera I still have and will keep forever.
So, my thoughts are not rational, but very subjective and has a lot with feelings to do.
So my second and alternative road could be to fulfill a digital SWC dream. A 50R have given me an economic possibility to consider this fulfillment.
But then how about a Z7? Yes that would the question then. Perhaps place a wonderful handfriendly mirrorless dream-Nikon at stand by...and let my FX-lenses still be used on the Df.
And keep the X-T2 (or later a X-T3) as the handy mirrorless
Buying both would be rather expensive....
Tomorrow the thoughts might be slight different, or not, time will tell...