There are other possibilities, but they are just as unlikely. For instance, Page and Brin could shut down Google, and keep it off until the NSA backed down. It won't happen. But, it's about as likely as a violent reaction.
Blood in the streets has more of a likelihood of doing something than Google giving up marketshare to Bing. The CIA did not pull out of Lebanon until William Francis Buckley was kidnapped - not even the Beirut bombings did the trick. There has to be a real human cost for things to change, and even then, it's a reorganization so they can say "The National Security Agency has stopped spying on the American people" while congress authorizes a trillion dollars for the formation of the National Security Association under seal. We were back in Beirut within 9 months. Go take a peak at Total Information Awareness. see if the Powerpoint doesn't have the same designer as PRISM. It certainly has the same mission, and we violently fuckin' killed TIA in 2003. Meet the new boss, same as the old boss.