Thanks Jorgen and everyone for all your thoughts.
After considering all the inputs received here I sold all the Fuji equipment (still have a X100s) and bought a D750+24-120 f/4.
I also "tested" the D500 at Photografica, here in Copenhagen, but ultimately decided against it. Mainly due to the slight advantage of the D750 at high ISO and the fact that I do not own any DX lenses. One of the reasons for selling the Fuji was to concentrate on building up my Nikon lens collection. Going DX would mean that I would at least buy one walk around DX lens (probably 16-80 f/2.8-4) and while I can mount that on my D810 it wouldn't make any sense to do so.
So far I'm quite happy with the D750. I was never able to get a shot like the one below with the Fuji, not saying it is not possible I just couldn't get it.
Many thanks again for all your thoughts.
D750+70-200 f/4