I know that the new lotr mordor game is only 6gb if you want to install the ultra high texture pack... Gamemakers and publishers definitely work with nvidia and amd to get their games to work on their cards.. So I don't see a brand new card not working with the newest games for at least a year.. As for me I still have a gtx 670 that has 4gb and am still happy with the performance after a year and a half..
You could also sli/crossfire down the road if you need more horsepower..
I'm really not that into call of duty style fps shooters, but I absolutely love this game! I've got a couple of friends with the game as well and being on the same team and leveling up really is satisfying whether you win or lose. There's so much customization of all your guns/perks/loadouts that it stays fresh.. I've played around 12 hours and still want to play more!