Not really. Even 980ti's in SLI have FPS drops down as low as 22 in GTAV and 28 in The Witcher 3.
http://www.maximumpc.com/nvidia-gtx-...g-performance/
Crossfire Fury X's perform better in GTAV, and in fact just really performs better at 4k across the board:
http://www.hardocp.com/article/2015/...5#.Vv6F3noRqVk
IMO, 4k is not really ready for gaming yet. Some games, FFXIV and WoW, you can do, but other games you'd be better off just running at 1440p. 1080p still really is the standard though, with 1440p being the high end and 4k being barely obtainable in most games. If you do really want to play at 4k though, I'd recommend a Fury X or a Nano. With the Nano, you can remove the power limit it has on it and it will perform somewhere in between a Fury and a Fury X while being cheaper. Currently, the AMD Nano is really the best buy on the market, but with the next gen coming out this year, it's really not a good idea to buy and graphics card.