It's no Y2K, but the PS4 clock battery problem is about as close to a hypothetical, dystopian future it can possibly get at this point. The issue, the result of an oversight in the PS4's firmware, could render all physical and digital games unplayable in the distant future.
Essentially, the clock battery inside of a PS4 is used to verify the time and date that Trophies are unlocked in order to prevent being able to alter when they were unlocked otherwise. Once it dies, players can easily replace the battery, though it must be authenticated by the Sony's servers before enabling users to play games. Like previous PlayStation systems, the servers for the PS4 will be shut down at some point, and if the battery dies and is replaced without connecting, PS fans will have to say goodbye to their game collection.
Similarly, frequent users of the PS3 will note that the aftermath of its PlayStation store shutdown hasn't been a kind experience. Players have noted that some PS3 game patches are entirely inaccessible, with some disappearing completely. As expected, the lack of patches is also tied to being unable to unlock PS3 trophies, re-downloading games, or playing online. There are few workarounds, but Sony has neglected to acknowledge the problems or fix them.
Despite the dark foreshadowing of an inevitable fate, the issue could be easily remedied by an end of life firmware update for the PS4 before Sony moves on completely. In some circles, even Sony's PS2 is a main go-to console, so it wouldn't be surprising to see the successful PS4 hold that spot going forward. Additionally, Sony likely won't be taking down its core online infrastructure any time soon, and the highly coveted PS5 is almost fully backwards compatible.
Nevertheless, for the less tech-savvy gamers who only want to pick up the controller, the issue is a frightening one. Even more so, if Sony never addresses the issue, replacing the clock becomes useless. With Microsoft making its own big moves against Sony, a nightmare scenario like this could leave a huge dent in the PS fanbase. Furthermore, it'd be a terrible end to the great legacy had by the lineup of PS4 games.
In any case, hopefully Sony fixes this sooner than later. The company is pretty focused on fully ushering in the PS5, though for many, the PS4 will be the go-to console for a long time to come.
Source: Push Square