Apple is reportedly considering expanding its music offerings in the face of declining iTunes sales, including the option of offering a subscription service. According to Billboard, the more interesting options being discussed include a Spotify/Beats Music-style paid subscription service for on-demand listening, and perhaps even a version of the iTunes store for Android devices.
Digital sales have decreased recently, with 2013 sales down 2.1% worldwide compared to 2012, while streaming music revenue was up 51% worldwide over the previous year. A significant amount of download purchases happen (or in this case, don't happen), in the iTunes store, so it makes sense that Apple is looking for ways to keep sales from eroding further.
Since these talks are qualified as "exploratory", there's no telling if any of this will come to be or if it's just a sampling of the ideas being kicked around between management teams.
Rumors of Apple starting a subscription service for anything and everything have gone round for years, and the cold water dousing those rumor flames was always Steve Jobs' claim that music fans won't pay for those subscriptions. Now that it's Tim Cook's ship to steer, there is possibly more to this story, including an Android app for the iTunes store. This would be music to the ears of industry executives who are reportedly convinced the growth of the Android platform is part of what slowed iTunes downloads.