It looks like PlayStation Plus was just the start. Head of Sony Worldwide Studios Shuhei Yoshida has stated, speaking to The Guardian (opens in new tab), that a content subscription model built around multiple tiers might become integral to the PlayStation 4's business model, with digital downloads certainly being the dominant software format.
"We’re shifting our platform more and more to the digital side – PS4 will be similar to PS Vita in that every game will be available as a digital download, and some will also be available as a disc. The Witness will be a digital release and because of the flexibility of the digital distribution scheme, we can have more small games that might be free or available for a couple of dollars, or different services like free-to-play or subscription models.”
He went on to explain the thinking behind those models and their delivery which, unsurprisingly, is where the PS4's Gaikai streaming technology comes in.
“So hypothetically we can look at different models – like a cable TV company. We could have gold, silver or platinum levels of membership, something like that. We can do subscription services when we have more content – especially now that we have the Gaikai technology available. With one subscription you have access to thousands of games – that’s our dream.”
It's highly doubtful that any kind of a subscription model would ever replace traditional game-buying on the PS4, but the extra flexibility, not to mention potential value, is going to be an interesting development to keep an eye on. Particularly in terms of its long-term impact on the wider gaming market.