According to this PS3F story, Sony has sent out a survey requesting opinion on how future Siren games should be delivered. From the piece:
The survey asks questions about Siren Blood Curse and asks people to rate various aspects out of 10. It also asks you whether you’d be willing to buy more games in the franchise in the future and how you’d like to receive them (either in one bunch, like Blood Curse or episodically.)
Discs are rubbish. If you received this, tell Sony so. Do the right thing.