I wonder how much this has to do with do not track and the search engines optimising towards people who don’t enable do not track / limit cookies.
Google's results for nearly every query are the pages that contain the most Adsense. That's how most results became "Best X in $CurrentYear" and top 10 listicles.
Google is going to slowly lose the powerusers first, and then like what happened to Metacrawler, Dogpile and Altavista, the decline will be RAPID as they convert their families and friends.
For that there needs to be a competitor that is clearly better. Which one do you have in mind?