RX 580 and an i5 3470?
RX 580 and an i5 3470?
It varies by game. Some may require it, others shouldn't. Overall it should work fine.
Yes, it will maintain solid gaming performance. The maximum frames per second will depend on your CPU, but it should work well if you're not aiming for 144 or 240 Hz.
Consider upgrading your PC soon or invest in a better one; otherwise, you might want to keep it for years and opt for the 580.