So, after some confusing messaging from Sony back in the day, followed by months of radio silence, the outlook is good. PlayStation 5 delivers comparable backwards compatibility with last-gen titles to Microsoft's equivalent feature. Sony's solution lacks some of the finesse and the sky-high resolutions of Series X playing One X versions, but clearly, it has advantages of its own. Before the arrival of Xbox One X in 2017, many Xbox games topped out at 900p vs 1080p PS4 equivalents. Series X can't break that 900p limit, but 1080p is what you'll get on PlayStation 5. PS4 Pro games may well have to contend with lower resolutions than One X equivalents, but in unlocked frame-rate scenarios, the boost to performance will be higher.
Really though, the key message to take from this piece is that PS4 users looking to upgrade to PS5 can relax. Your games will work - and then some.