I think there's also a problem that the quality of content that Google has to index is steadily declining. In the 90's, many people were keeping lists of links to good stuff they found on the internet. Google could crawl the links and make conclusions. Now, people hardly do that anymore because they can just google it.
So Google has to employ ever more powerful algorithms to maintain even the same level of search quality. I think here lies an existential threat to the search engines.
I think there's also a problem that the quality of content that Google has to index is steadily declining. In the 90's, many people were keeping lists of links to good stuff they found on the internet. Google could crawl the links and make conclusions. Now, people hardly do that anymore because they can just google it.
So Google has to employ ever more powerful algorithms to maintain even the same level of search quality. I think here lies an existential threat to the search engines.