I don't think the smartphone is much of a real alternative for a photographer. It's convenient to snap shots of people and things that you see and but the user interface is poorly suited to the task and the optics are very limited in capability.
Now that the D500 supports continuous transfer of images to a phone, you can just shoot normally and have the same convenience of e-mailing the images or posting them online as you would with a smartphone. At least if Nikon's software works well. Previous implementations had the drawback that you had to establish the connection every time and the software is very limited in functionality. Hopefully with the new generation this will have been solved. Of course then there is the problem that this is just one camera so far (the D500) and it'll take a while for this functionality to be integrated into other models.
Personally I prefer the "slow photography" approach (where images are meticulously planned, executed and edited before anyone gets to see them) but cannot deny that there are merits to sometimes being able to do it very quickly. Also, in the studio, I want to see images immediately after on the big screen, without using a cable (simply because experience has taught me that if there is a cable, someone will trip on it). These functionalities should be as easy to use as possible. I think Nikon gets it but they are too slow to implement it in a truly fluid manner. I think it must be because of their limited software development resources (and their apparently limited know-how related to programming on a general purpose computer with other software running at the same time and greatly varying configuration options both software and hardware).
E.g. the D750, D7200 etc. really need better applications for phone operation than Nikon is providing so far. But perhaps it's just too early. Anyway I think for Nikon's success in migrating new generations to use dedicated cameras instead of (or in addition to smartphones), the fluidity of co-operation between the two devices is crucial.