> If Spotify became their own label and signed 100 of the top artists, their old songs are STILL with the previous label and will likely never leave. Spotify still NEEDS those songs or it's SOL.

As I pointed out in a sibling comment, I think Netflix actually has the same problem. There is a significant presence of long-running shows that people love to watch on Netflix: Friends, Breaking Bad, Modern Family, How I Met Your Mother, etc.. A big favorite "It's Always Sunny In Philadelphia" just left the catalog - presumably due to the acquisition of FX by Disney - and "Archer" will likely soon follow for the same reason.

A lot of those are not new and people still watch them (either to catch up on a missed cult hit or to rewatch their favorites), and the will continue to do so for the next 10-20 years. As long as that's the case Netflix also has to continue to make deals with the existing rights holders or substantially shift their core offering.