I have had GPUs fail. But I use them until they die. I ran dual 6950's for years. They worked the entire time. I then wanted better performance and upgraded. I recycled the cards to my kids computer. 1 card died. Getting artifacts on bios. Pulled the card, the main card works fine.These cards are 6+ years old.
Also, same thing with an even older card. This was from like 2000. It was a 9700 pro. I used it for years until the fan died and it overheated and cooked.
So, in the end, GPU's have a failure rate of 100% given a long enough time line. In my opinion if I get 5-6 years of use out of them I am very happy. All GPU's should last you until they cannot run newer games. This is considering you overclock or punch the card.