How long will the Ryzen 5 5600X3D remain good for gaming?

It depends heavily on what you consider acceptable. Some players already find six cores limiting in CPU-heavy games, while others are still happy with much older systems. If you mostly play a backlog of existing games or use a sensible frame-rate target, the 5600X3D could stay satisfactory for many years; if you want high refresh rates in demanding new releases, you may notice its limits sooner.

There’s no exact expiration date. It will remain useful until the games you play no longer deliver acceptable frame rates or smooth frame pacing. The 3D cache gives it a strong advantage in gaming, and most current games don’t gain enough from a modern 8-core CPU to make 6 cores automatically obsolete. Your settings, GPU, resolution, and expectations will matter more than the core count alone.

For typical gaming, 6 cores and 12 threads should remain viable for quite a while. Newer games may eventually favor 8 or more cores, but it’s difficult to predict when that will become a widespread requirement. The practical answer is to keep using it until you actually see stuttering or frame rates you aren’t happy with.