There isn't a lot we know for sure about the PlayStation 5, but we do know that the PS5 will be backwards compatible with PS4 games. The PS5's backwards compatibility seems as though it will be a key component of Sony's next-generation strategy, as it's been revealed that the console will support cross-gen multiplayer, with PS5 users able to play with PS4 players online.
This news comes from PlayStation deputy president John Kodera. While some may have assumed this was the case anyway, others will be happy to have confirmation from Sony itself. Allowing cross-gen multiplayer should go a long way in helping players transition from PS4 to PS5, and it will also be another selling point for Sony's next-gen console.
The full scope of PS5 backwards compatibility has yet to be revealed, but it sounds promising so far. The best case scenario would be that one would have immediate access to their entire PS4 digital library on the PS5, but it's possible it will be something more akin to the Xbox One backward compatibility program, where some games aren't made compatible for whatever reason.
Most estimates peg the PS5 for a November 2020 release date, and so it's hard to say exactly when we will learn more about its backwards compatibility with PS4. If Sony decides to have a full showcase of the PS5 at PSX 2019 as has been rumored in the past, it's possible we will learn everything there is to know about the next-gen console's backwards compatibility by the time the year is out.
Alternatively, we may have to wait longer for news on the PS5's backwards compatibility and other features the new console is bringing to the table. While it's skipping this year's show, Sony is expected to be at E3 2020, so maybe we will learn more around this time next year.
Whatever the case may be, it does seem as though Sony is going to use backwards compatibility as a selling point for the PS5, and so even if the PS5 launch titles are underwhelming, early adopters should still have plenty to play.