Is Search _really_ so positive-returns-to-scale that only a single player <i>can</i> exist?<p>I mean, yes, Google&#x27;s percentage of total Web search <i>is</i> embarassingly huge (north of 80%, or is it 85%, last I checked). But the user lock-in is slight.<p><i>Advertiser</i> lock-in is where I strongly suspect the action is, where Google offers both networks and tools which appeal to online ad buyers in a fashion that&#x27;s difficult or impossible to match.