If it's anything like most digital marketplaces, they don't need a patch to do that. They can just revoke the license, and in some cases delete it remotely without warning. (An eBook retailer pissed off a lot of people when they deleted books off of people's devices, at one point.)
I just realized P.T.'s about to get a lot more mysterious to people in the future now, unless they stick it on a future disc or something. Not quite Polybius, but like a Ring-style VHS tape.
"A friend of a friend has a copy of P.T. on an old PS4. They said it was TOO scary, and so the lead developer quit and they pulled it off their network."
"That's not true."
"It is! His brother keeps the PS4 locked up safe, and whenever he's asked about it, he just whispers, 'A Hideo Kojima Game.'"