I have AM4 systems with Ryzen 5950X and 5900X processors, 32GB of DDR4 memory, and a Radeon 9070 in the gaming PC. I play mostly single-player games at 4K and use Visual Studio, Docker, virtual machines, and WSL.
I skipped AM5 partly because of cost. How long might these systems remain useful before performance or support becomes a problem?
There isn't a useful expiration date for AM4. Those are still capable processors, and for single-player games at 4K the graphics card will often matter more than the CPU. Being comfortable around 40 fps with variable refresh gives you more room than someone chasing very high frame rates.
Some games will still hit the CPU hard, especially ones with lots of entities or complex simulation. Several more years seems plausible for your stated use, but a specific number would be a guess.
For development, watch memory usage before assuming the platform is the problem. Visual Studio, WSL, containers, and virtual machines can add up, especially when several are running together.
If you're regularly running short of RAM, moving beyond 32GB could be a worthwhile upgrade without replacing the whole system. Check your motherboard's supported configurations and available slots first.
Performance and support are separate questions. A PC can feel fast enough while a future operating system or application drops support, or it can remain supported but feel slow for a particular workload. There's no reliable date here for either outcome.
Hardware failure can also force the issue before performance does. I'd keep backups and check the availability of a compatible replacement motherboard if keeping these machines going is the plan.
Don't overlook connectivity. If you eventually need a peripheral or expansion option your compact motherboard can't accommodate, that could push you to a new platform even when the CPU is fine. Check the exact board's ports and expansion options against what you need.
I wouldn't replace a 5950X or 5900X just because AM5 exists. Wait until a game, build time, or other task is measurably bothering you, then compare the cost of an upgrade with replacing the platform. Future component prices are anybody's guess.
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Farnix.4v:
Emulators can be a different story too. The demands vary a lot by emulator and game, so 4K performance alone won't tell you whether the CPU is enough.