what is your current GPU and monitor, and, chosen resolution for gameplay?
For instance, even a GTX1060-6GB is more than enough for 60 Hz monitors at 1080P res....
At 4k, however, a 1080Ti is quite desirable..., but at 1440P, the 1080 rocks; if the next gen 'hypothetical 1170-equivalent' is as fast as a 1080Ti for $100-200 less dollars, waiting might be advantageous...
I've not seen any performance leaks or rumors yet, however, so, at least the 1070/1070Ti/1080/1080Ti's performance is known.