Sony was granted a patent for a multi-layer disc that could feature a BD-R or BD-RW layer.  So one layer would feature content, like a game, and another layer would in an area reserved for storing user information, be writable with perhaps console and user data. 

While the chip itself may prevent piracy, the ability for the PS4 to write console or user specific data would lock the disc to one or the other.  In addition, the drive wouldn't necessarily have to be a Blu-Ray writer.  The writable layer could be DVD-R/RW or CD-R/RW, as well as BD-R/RW.  So the drive could feature an inexpensive red laser for writing data to a DVD or CD layer, rather than being an expensive Blu-Ray writer drive.

In my opinion this is by far the more interesting anti-piracy/second-hand measures as it puts all the information right on the disc itself rather than putting it on a database that can or can't be called depending if the console is online or not. 

http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&p=1&u=%2Fnetahtml%2FPTO%2Fsearch-adv.htm&r=1&f=G&l=50&d=PALL&S1=08363531&OS=PN/08363531&RS=PN/08363531

While I wouldn't agree with locking the disc to a specific console/user, I think having anti-piracy measures on a proprietary layer in the disc is a good idea. It would be a major hindrance to piracy as that data could not easily be reproduced onto another disc with a standard burner. If it's physically unreadable in a standard disc drive that would make it even more secure.

You just made me think of something. An RFID tag embedded in a disk...

If you haven't been keeping up on things, that appears to be what Sony is already planning on doing.  There was another patent that showed the chip on the disc.  So it would appear it'll feature somewhere next gen for Sony.  Where I'm not sure.

you probably just read that already some weeks/months ago

Have a universal system for locking out content for second-hand games. If you want to unlock lets say, the online portion of Battlefield 4 then just do quick $10 "microtransaction".

Make it easy and not as annoying as an online pass.

I can't imagine why you would block out an area on the disc to be burned for user data otherwise. 

One thing to keep in mind, is that Sony could make the discs R/W, but just not in a console.   So you could still take it in and sell it, but GameStop or another second-hand store would have to pay a fee to unlock the disc to clear off the data.  Then, eventually, after so many uses it would be worthless.    For instance, if there is enough space for 5 people to write user/console data to the disc, it wouldn't be reusable for anyone else but those five people.

Depending on how the RW is implemented, it would be possible to have it so that the usable space is limited to only so many users.  The previous user info could be "erased" but it still takes up space on the disc.  Or the entire area is reusable, but a counter is kept elsewhere that limits the number of times the disc is written.

No, I worked in RFID so when I read the title it came to me. I wasn't aware it was in the works.

I don't mind if they use this to combat piracy, because much like this gen the file sizes required is just not worth it.

Don't screw over used games though, there have been so many times when there was no other option but to buy a used copy especially for games that came out early on in the gen and are not in production anymore.

I couldn't agree more.