Nicely timed inquiry. As a geezer who's thrown in the towel on non-Nikon stuff and just decided its easier to have one set of lenses to use on different gear using the same mount, I share the objective and in the last few weeks been shipping off gear, and taking in new. I call it rationalizing and yeah.... it's all about compromise. Had some AI-s lenses until I realized the 3-year-old grand daughter was most likely going to be better captured with a series of AF/D's (24/50/105 - 'cause you can take manual focus out of the boy, but you can't take prime out of his lightweight rides). Yeah. And so the Contax went out, and in came some Nikon with an FM2n, F100 and D750 on the way - all from KEH.
Thinking seriously of ditching the Sony A7r2 and Zeiss Loxia lenses, too. Researched the Nikon Z's and decided to snooze on that until they figure it out a bit more. Like the intention, but both Fuji and Sony had to figure their ways around, and they have a bit of a leap ahead at the moment. FWIW, Fuji is nice and 24MP is fine even on their APS-C's - fine enough to produce beautiful prints from JPEGs at 17 X 22. Didn't think it would work, but it did (thanks to tools like Epson's SC800 and some hard work in post). That said, I don't think at the end of the day, you'll be all that happy with adapted lenses. I'm not even happy with Nikon's plastic tennis cans.... the glass is fine, but put it in an aluminum tube and my fingers would like it better. Ah.... the compromises we make? Yep.
I'm more willing to compromise on the body than the lens, and yet here I am, and pushing myself back towards some digital that ain't an iPhone. If you don't see it as primary and film remaining your main deal, then maybe you can live with it. But why not wait for round two? Sony A7's were quickly superceded and Fuji was no slouch in pushing to trade up either. Neither Sony nor Fuji are as good as their fans nor as bad as their detractors. They're all fine. The one thing that could change the Z-appeal might be if the lenses kept the ability to manually focus, or maybe Zeiss kicked their Loxia-type line over there. But I'd wait. Mirrorless is nice for constant view... but maybe I'm weird (maybe?) but I don't really chimp or use the rear screen, and so the virtues are continuous view and silent shutter. Not to be sniffed at.... that's what we do RF's for usually. But as context, I'm trying to hold the whole camera thing to $1,000 these days unless there's a real reason.... and so I'm actually a fan of used digital... or digital's that's NOT the latest and greatest but getting superceded (witness the willingness to do a D750). Film remains my love, and I'm shooting mostly MF, but with a move, remodel, and a bit of chaos over the next few months, more inclined to deal with some 35mm and digital again.... of necessity with a Jobo, Coolscan, and all the rest in storage. So Nikon feels like going full circle... and the F100 my (probably fruitless) effort to resist the sweet looking specs on the F6.... which seems to be out and about for about a grand and posts all the shooting data most film cameras miss - if you don't have a pen and notebook.
Bottom line: Throw my hat in with the wait crowd.... or sell it to me when you're done.