Journalism isn't shrinking because of social networking, it's shrinking because the internet has made every news outlet available to everyone.
American news operations don't have much in the way of foreign bureaus anymore, but that's because on a day-to-day basis they don't provide better content than we can already get from news media actually in foreign countries. Want to know what's happening in Britain? Surf over to the Guardian or the Telegraph. The Middle East? There's al-Jazeera. Ditto for just about every other place in the world, which has media of its own that can be mined for information a lot more cheaply than sending an American over to do it in person.