Here's the thing. Apple now has over 1 billion active devices. I'm not sure how many active iTunes accounts that is but its for sure hundreds of millions. It makes sense for Apple to be thinking how they can monetize this user base (and hopefully keep them as Apple customers), especially if hardware upgrade cycles are getting longer. I might not be buying Apple devices as often but I'm still giving them money for other things like Apple Music, subscription TV service, etc. and I'm sure Wall Street would like it because it's a more predictable revenue stream. Honestly I'd love it if Apple turned their devices into a subscription service similar to the iPhone upgrade program. I'd totally pay a monthly fee to "rent" my devices (with the option to own outright) and get a new one every year or two.
1 billion active devices, yes, but not necessarily 1 billion unique users.