Wrest control of the algorithm
There's an argument that users, in sufficient numbers, can ultimately do a better job, but, of course, the pages have to get in front of eyeballs first and the users' "thumbs up" and "thumbs down" would have to be reasonably objective, which might be a fly in the ointment - not to mention that getting their opinion in-context would mean mandating content on the pages or adding features to browsers.
There is, I think, another, perhaps more fundamental, flaw on the horizon. The purpose of advertising is to get the attention of sufficient numbers of appropriate people for long enough to deliver a commercially-significant message. How do you do that when there is a seemingly infinite number of billboards, most of which are advertising other billboards? It's not just the increasing uselessness of search engines, it's devaluing the advertising market itself. That's great for magical food supplement market, but it's not going to help flog soap powder and the latter, ultimately, is where the money is.
Whereas there are things Google can do about that, to a greater or lesser extent they break the funding model for the Internet - and, indeed for Google itself. That may not be a bad thing and you could argue that's it's broken already, but we don't have any alternative lined up - and particularly no alternative that could fund search in the absence of its being directly coupled to advertising. And without search there is no content to speak of because we can only speak as we find.
We've already seen what happened to the print media when its advertising went elsewhere. We may be about to see what happens to the online advertising industry when content disappears.