User experience has always been important to SEO—at least to some degree. Google favors sites that are properly optimized for mobile devices, ones that load quickly, and ones where it's clear that users are enjoying their experience (with prolonged time spent on page, etc.). But in 2017, we may see an increased emphasis on user experience—especially as it relates to mobile devices. AMPs, which I've already mentioned, could be the first sign of this, but look for other ways that Google will favor pages that offer better user experiences overall.