Rough for Spotify - since Apple is including theirs at no extra cost, it becomes tough for Spotify to justify charging extra for it. So it goes from a feature that makes them money, to a feature that instead costs them money in engineering resources and bandwidth, before they even release it.
That depends if you believe Spotify users will switch to Apple just for that feature... if they won't, Spotify can likely still charge extra for it. Folks are pretty tied in to ecosystems at this point: if you've bought audio hardware that supports Spotify but not Apple, you're not going to switch.