I think the biggest part of what people are missing is that the developers are getting SOLID 60 fps with a GTX 980 at 1080p "Uber" or Ultra settings (sans Hairworks). That doesn't mean the video card is only producing 60 FPS. It means that the game is producing EQUAL or MORE than 60 FPS. I believe that even people with GTX 970, 780's, will be able to play this game at 1080p Ultra (sans Hairworks) - but they will not be at 60 FPS (probably SOLID 30 FPS though), which can easily be tackled by overclocking which is actually very easy and do-able on NVidia Cards.
So I believe when it comes down to it, if a 770 with 2GB of VRAM is recommended for 1080p @ High, a card with 3 GB or more should be able to handle Ultra. And if you overclock, you might be able to get 50 to 60 FPS.
P.S. - I believe everything I said also applies for AMD, it's just I've never owned AMD cards, so don't wanna say anything about their performance.
So I believe when it comes down to it, if a 770 with 2GB of VRAM is recommended for 1080p @ High, a card with 3 GB or more should be able to handle Ultra. And if you overclock, you might be able to get 50 to 60 FPS.
P.S. - I believe everything I said also applies for AMD, it's just I've never owned AMD cards, so don't wanna say anything about their performance.