A DJ that will automatically mix your playlists and beat synch them should be added. I am talking beatmatching and smooth transitions between songs.
This is how you set yourself apart from other streaming services. Having freinds over? Load up a playlist and have spotify take care of the rest. In the car? At the beach? really anywhere you want a smooth continous mix.
There is an app called Pacemaker which can do this now by using an AI to match up songs. Spotify should do this within the platform, like a step up from the crossfade.
This will be a definite way of setting you apart from the competition, and an amazing feature.