The answer is never. The U.S. Isn’t going to start assasinating American journalists involved in a such a high-profile story. Dropping bombs from so high above remote parts of Yemen or Pakistan that no one can see you is one thing. No one’s likely to be assasinated in this episode. What is likely is that the U.S. will pursue all means necessary to extradite Snowden to the U.S. where he can face a very pro-forma trial in which he is not permitted to raise any whistle-blower related defenses and faces the mostly pre-determined verdict of guitly-as-hell-traitor-spy.
Also, Glen Greenwald said in a recent interview on NPR Fresh AIr that they’re working on a bombshell story based on as yet undisclosed Snowden archive documents. Stay tuned.