tldr version (although I highly recommend reading the whole thing): Search is relevance + reputation. Reputation is the hard part. Communities must/will come

tldr version (although I highly recommend reading the whole thing): Search is relevance + reputation. Reputation is the hard part. Communities must/will come around that assign reputation to their members. Google (and search as we know it) will be replaced by something that will calculate reputation of the communities, not the individual members.