This game uses OpenGL? I'm kinda surprised, I'm used to most things being done in DX11 these days. I'm also a fair bit disappointed at the AMD performance for this game if what people are saying is true. But on the contrary, I'm very skeptical of GTX970 performance... over 100fps average at 1080p? A little over 60fps average at 1440p? Okay maybe it's not so crazy considering MGS5 runs very smoothly at 1440p on a 970.
But then it also puts things into perspective for Vulkan and that GTX 1080 thing. Unless it was running at higher resolutions like 1440p and up, it's not particularly impressive considering the 980ti averages 150fps at 1080p. Maybe Vulkan isn't quite as well optimised as we hope? Or perhaps it's the 1080... could be unoptimal drivers for an unreleased card. Whatever the case, I hope performance is good on Vulkan when they release that feature.
Or, you are comparing the 1080 at stock boost to a well clocked 980ti, which means the 1080 wont be ahead of the clocked 980ti.