Yes, those 8GB and the "GD5" naming point to a GDDR5 card.
Now the question is if AMD will save Fiji and HBM for a Titan X killer card (a user on another forum called it Zeus, because Zeus defeated the Titans 
), and the driver leaks all but confirm that the 290/290X will be rebranded as 380/380X, what will be inside those 390 and 390X cards?
I think that AMD will go for a Hawaii chip with the improvements made with the 285's Tonga, a 2GB card that competed replaced the 3GB 280 card offering roughly the same performance while using less power. With those improvements and refinements, AMD could afford to add the extra 4GB and slighly bump the frequencies making them a lot closer to Nvidia's 980.
Or AMD is trolling us and has managed to make an 8GB HBM Fiji card 
.
Please excuse my bad English.
Currently gaming on a PC with an i5-4670k@stock (for now), 16Gb RAM 1600 MHz and a GTX 1070
Steam / Live / NNID : jonxiquet Add me if you want, but I'm a single player gamer.
