And still in 2017, some things just look better playing from physical media. Sad.
It's going to be a long time before we can get to a point where all content is using an efficient 4k stream and Atmos sound. This is why physical media still has the big advantage, it's the closest thing to having all content under one format. The only thing you can't get that I am aware of is Netflix 4k blurays(I guess Amazon originals as well) but the 1080 bluray version of Netflix shows are just as good if not better than the 4k stream from what I read.
With that said the UHD Blurays will still be the ultimate in quality but I did read the Vudu versions are impressively close and beat out 1080p Blurays which is a good sign of the potential of the tech. Its gonna be years before we see massive amounts of shows and movies that can use all of this.