The Fury card was leaked a long time ago it won't be under $700 USD, so I'd say $800 USD seems realistic (if the leak was correct).
As for all of the information we can get from the 3D Mark screenshot, I can say that AMD might have killed the 980 for multi GPU configs. We all know the 290X get to 980 level when using high resolutions, so the 390X with 8GB will beat (I think) the 980 every time on high resolutions: 4K or triple monitor setups.
Cheers!