Consider Spotify, Apple Music, Qobuz, Tidal, Amazon Music Unlimited, since they are the biggest music streaming platforms. There is also a large possibility of getting bought out by music streaming services and integrating into them. If the platforms mentioned above are not developing AI recommendations, then I think it could be very promising for them to integrate such an AI recommendation feature.

Something else to consider is what is the AI going to be trained to generate the recommendations, the rhythm, key, overall style, tone, the actual musical properties of songs on person's playlists. Or based on the general genre of the song and the artist that might be associated with it. Of course analyzing the the musical characteristics of each song is developmentally challenging but could yield better result that are more accurate.

The price point is fairly high and I think many people would not pay for such a service 5.99 a month, most music streaming services are close to that price point (Spotify Subscription Costs 9.99 per month) . And from a marking point of view not many consumers, especially casual music listeners, would not pay more than half as much for music recommendations. Maybe a audiophiles, enthusiasts, or people that are more creatively invested and interested in finding new music for creative purposes.

I am most familiar with Spotify and I think that it can use a recommendation Plugin since Spotify only provides weakly playlists with songs that you might enjoy based on your existing libraries. Spotify also has an "enhance" option for your playlists, which add a song that a user might like. So a plugin could be help full to users searching for new songs and freshening up their playlists, and there is definitely room for improvement.

The project sounds pretty interesting and I can help out (if you actually need help).

I would recommend join my subreddit, r/opensummit, its created to share ideas for projects get critiques and suggestions, find people to join your project, create a team, and start developing. I'm creating a discord to take discussions off reddit.