Any way you look at it, Google is a powerhouse. It's the world's best search engine -- simple, fast and relevant. In YouTube it also owns the site that originates the second-most search queries. Its market share increased again in 2008, and it has so badly outflanked its largest competitor that Yahoo's highest hope for securing its future revenue was to have Google sell its ad space. Google is a company that is built to last, branching and pruning its business with a never-ending series of beta tests that allow it to grow and constantly evolve.
What could go wrong? The answer is: a lot. And it could go wrong very quickly. Look to history for the evidence.