You already have a pretty good card right now. If I was you I would not consider 980 and 390x at all, because you don't gain as much to justify the cost. Next week non-X Fury comes out, could be interesting for you. Otherwise, next-gen GPUs are coming out in about one year at the earliest. Since they will have the benefit of 2 process node shrinks, I expect for them to outclass the current high-end GPUs. There is nothing coming in the meantime (in the high-end), except perhaps more-or-less cut down versions of existing chips, so make you choice now and stick with it. Don't go buying a 980ti in spring of next year just so you regret it a few months later.