How long will a R9 390 last?

I can't believe people post questions like that on here. There's too many variables that factor in the life of a video card(case fans, room temps, keeping the card fan/s cleaned etc.) Please do a little research before asking us on here and use common sense.
 
My old 5870 is pushing 6 years(It is in another system and still used quite often). Was worth every penny.

Sure game settings have to be reduced, but for a card that old, It held up pretty well.

I have only had a single video card actually fail while it was still useful for gaming. As said above, all systems are different so one user may kill a card in a year while another may have it for several without issues.