"search engines and every website with user generated content on a larger scale would have to close down."
Oh darn. I'd be thrilled if that happened. No user generated content here, and we were literally doing 10 times the traffic before Any of the big 3 SEs existed than today. Can't wait! Direct-type / direct-match domains and personal favorites lists RULE(D)! Although without SE's I guess a lot of people who ONLY do SEO may have to find new ways to make a living.
But back to the other trend in this thread. I wouldn't be surprised if G COULD afford to review everything they include in their index. They have been constantly narrowing the index by eliminating duplicated (in THEIR opinion), shallow (AGAIN in THEIR opinion) and scraper content (that comes too close to their own) so the next step is to simply manually weed out the remaining .01%. Perhaps it will turn into (as it has been turning all along) that they ONLY include content they have reviewed first and trusted enough to make authority (pretty much what we have now), thus shutting out a large part of the net. Oops, they're already there. Either that or they will leave it to their website developer slaves (us) to do for them somehow. I see a day real soon where they stop showing so many results per search (maybe 50 max) and only show up to the number of results beyond which they no longer have paid ads to cover, perhaps interleave them every other one. Imagine how much big advertisers would be willing to pay for that! (Oops, now I went and gave them the idea!)