I want a gpu with great value and I was thinking about a rx580 8gb, good price for its performance. But I wanna know if this gpu could run games that will come in 5years on full hd, if doesnt, I would buy a 1660 or you can recommend another gpu to me tho. Srry for bad English ^^
There is NO GPU which can called as future-proof. It all depends on the Game being released/played, and it's ENGINE. Hard to comment whether your GPU would still be able to play games released within the next few years or so.
If you want to probably be able to run all games maxed out at 1080P 60Hz for the next 5 years you pretty much have to buy the best GPU on the market. A 980 Ti that I bought used is 4 years old and while it was a "4K" GPU when it came out it now is pretty much a 1080P card