1080Ti it self should not influence 1070 and 1080 pricing.
It is more likely, that the prices of GTX1070, 1080 and 1080Ti depend on how AMD new gen GPUs perform and are priced.
e.g. (wishful thinking) If AMD's GPU like the one used during CES demo is priced below GTX1070, nVidia will be forced to lower down those 1xxx cards.