depends on a lot of things
first with your gpu at 1080p is my guess are you happy with the proformance and are ok with waiting for a better card
2nd pc specs and budget?
3rd are you planing on doing things like 3d modeling or video editing or is this only a gaming rig and are you planing on upgrading your resolution?
4th anything wrong with the 1070 to you or are you a amd fanboy
5th for you a 480 from a 380x is not a huge upgrade as a 380x is between a 960 and 970 and a 480 is near a 970 in proformance