End of this year according to http://www.kitguru.net/components/graphic-cards/anton-shilov/nvidia-to-reveal-geforce-gtx-970980-with-8gb-of-memory-in-november-of-december/
But I don't get it. You only need 8gb for multiple 4K screens. And gtx970 (even quad sli) wouldn't run multiple 4K screens anyway.
The way texture sizes are increasing, it won't be long before we cross 4GB. It i not about the frame buffer I am worried about, but the size of the textures when you into the ultra territory these days.
I am not worried about 4K, like i said not the frame buffer, but future texture sizes, I gauged that Shadow of Mordor already eats 3GB of VRAM on ultra texture pack. Anyways, gonna wait for 8GB VRAM version.