According to Gamespot, Sony has researched and filed a patent for new technology that could be implemented to block previously used games.
A patent application, No. 20130007892 for an “Electronic Content Processing System” and “Use Apparatus” would associate individual game discs with matched user accounts. The patent’s abstract more specifically states
“A game playing system includes a use permission tag provided for use in a game disk for a user of a game, a disk drive, and a reproduction device for reproducing the game.”
It further states,
While no gaming console has been specified in the patent application, it is speculated that the patent is intended for Sony’s as of yet unreleased Playstation 4 system. This patent has sparked debate in the gaming community about the issue of the second-hand gaming industry, and gamers’ best interests versus corporate profitability.