What's the worst thing that could happen to Google?
vseloved: It has already happened: they've screwed up search, when moved away from PageRank to some reputation-based algorithms (and set-up the Facebook & co. as sites with biggest reputation, which is nonsense, as that's UGC). It's not so visible in English-language search, although begins to be, but, for example, for Russian I've stopped using it altogether.