As mentioned above, we do not know much about the PS5. However, backward compatibility is more secure, at least if a patent recently filed by Sony Interactive Entertainment comes into question. The patent not only suggests that the PS5 is backwards compatible with the PS4, but also with the PS3, PS2 and the PS1
I personally believe that both the PS5 and the next Xbox will be backwards compatible. I am not sure how extensive and far reaching it will be, especially with the former. Microsoft has already shown an impetus to accept its legacy and unite its platforms under one roof, but Sony has not.
As always, all speculations and forecasts – including from industry analysts – should be taken with a grain of salt
And of course you're welcome to leave a comment that tells us what you think. Is the PS5 backward compatible?