Google will not be brought down by a single entity. Companies can do better with individual parts than a jack of all trades.
Google will be brought down when someone emerges with a better or equal (but more anonymous) search engine. That's all it will take.
95%+ of google's revenue is from advertising streams ... of that PPC (search) and adsense are a huge chunk. If searchers quit using google, the beast will fall because their PPC rev. will plummet. The content network will follow when another massive player emerges.
At that point, they will lose momentum and spiral downward since stockholders will be going crazy and demand changes.