We double-checked whether Sony is being cute with its DRM plans and might actually be matching Xbox One in allowing publishers to block used games -- despite not blocking used games itself. We asked: Can third-party publishers restrict used games on PS4 even if Sony won't?
Sony says: “Our used game position for PS4 is exactly the same as PS3, which publishers and consumers broadly support today. In fact, all publishers we’ve spoken to are in agreement with our position.”
Publishers can still do online passes to restrict multiplayer, although Sony has dropped that.
We would love Sony to flat-out say publishers can or can't block used games themselves, but it seems that this answer is the best we're getting right now.
Take a tour through Sony's statements on PS4 used game DRM here.