As much as I like an EVF option and wish Nikon could have offered an optional EVF for the hot shoe, I am looking forward to seeing the improved viewfinder. It is still very useful for previewing a scene without Live View.
Clearly confirm your entire view — 0.75× optical viewfinder
The D850 provides a wide field of view for easier subject confirmation with a 0.75× magnification* for its optical viewfinder — the highest ever offered by a Nikon FX format D-SLR.
The viewfinder has been redesigned to employ an aspherical lens and a new condenser lens with refined refraction, allowing for a slimmer body while keeping a sufficiently long eye point. Its high-contrast viewfinder information display uses organic EL display elements, making it easier to read even under bright sunlight.
* 50mm f/1.4 lens at infinity, -1.0 m-1.