That's fine. Its really hard to get good frame rate in 4k today. A lot of that isn't just the GPU (eg: poorly optimized games, CPU, I/O, etc), but if it can do 8k 60fps reasonably consistantly on paper, then it can do 4k@60fps+ consistently for real (assuming nothing else is the bottleneck).

That makes it worthwhile. That's personally what I was waiting for before upgrading my 1080 GTX TI and my monitor.