I mean, they're already doing exclusivity contracts for podcasts (eg. Joe Rogan on Spotify only), it's going to be a small leap to go to artists being exclusively on one service, and before you know the labels will all start their own streaming service, so you have to have different apps for Sony BMG artists, another app for indie artists, etc.
The enshittification is mostly pushed by wall street, who want instant bigger profits, and they're happy to kill the goose that lays the golden eggs in the process. Spotify is not immune to those pressures.