Given the market wants a better video card all the time...
AMD only recently brought Polaris 10 and 11 to market
so I am figuring like other x90 such as the HD 7990 and H6990 which are dual gpu cards so what not slap 2 Polaris 10 chips on a board, use a dual fan cooler to keep the card length under control and underclock the logic a bit to keep the power under 275W
this could be sold for $499 easily and could kick NVIDIA to the curb with the better card.
DX12 can leverage swarms of gpus so why not stuff the rig with dual gpu cards