Tidux shared a link to an updated Sony patent (with another HERE), which means according to reports the PS5 may offer backwards compatibility and play PS4 games on the upcoming PlayStation 5.
To quote from PSU.com on this interesting discovery:
"PS5 backwards compatibility is looking a little more likely after a US patent was updated by Sony Interactive Entertainment America. Updated on February 13, it clearly states: “Backward compatibility testing of software in a mode that disrupts timing.”
This isn’t confirmation that the PS5 will be able to play PS4 games, but it could be an indication that Sony is conducting some kind of backwards compatibility testing."