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I think you're wrong that the biggest worry is the organized movement. It's the conditions that make that movement possible and successful. It's a question of framing, but I think an important one. You could imagine defeating the neo-cons, and having them reform as a new coalition, since the political conditions and structures haven't changed. It could be on the left or the right, even though the right is more likely (but they have been on the left before).
It's an important distinction because we (Americans) have a tendency to idolize our political order - the Genius of The Founders, the Perfection of the Constitution, etc, and so many of us are blind to the failures of our system. And the frustration dealing from that inability to openly recognize those problems, the need to project and disassociate ourselves in the face of the rational contradictions, is the basis of the mass-character of the threat.