As well, I don't believe Wikipedia is all that unique. While it may have been (one of?) the first wiki encyclopedia, and obviously now it has a huge amount of content, there's nothing inherent in Wikipedia that couldn't be recreated if necessary. I don't think the Internet would implode if Wikipedia vanished tomorrow. Would I be inconvenienced? Yes. Would it take years to build a new Wikipedia? Yes. But it's not so vital to the Internet. Whereas if Google had never existed, I think the Internet would be far different.