B&H has a great article addressing this issue here:
While I am intrigued by the idea of a dynamic layout to my viewfinder, the small body size, lack of physical controls, and poor battery life detract me personally right away. Not to mention a pretty wide lens investment to replace- leaving the DSLR, and the Nikon F-Mount seems implausible. Although getting adaptors and trying an alternative solution while still shooting with DSLR bodies sure seems like viable option.
As for me, the Nikon D850 will suffice for MORE than a LONG time ahead!! But the competition from Sony & Canon are quite notable and far ahead in some aspects!