The company is adamant that desktop-only sites won't vanish from the index, and that phone-optimized sites included in the first wave won't have an advantage over either desktop content or mobile pages that have yet to be included. And if it happens that a desktop site is more relevant to a given search, you'll still see it ranked higher than its mobile alternatives.

Even with all these conditions, there's no question that the tide has turned. Google had already emphasized mobile-friendly pages when searching on phones, but it's now using them as a reference point for the search engine itself. It's a not-so-subtle hint to site creators that they should fine-tune their pages for mobile if they want to stay in sync with Google's priorities.