I think the state would rather keep their communications secret, but in the event that they cannot, they will continue business as usual rather than change what they talk about. Really, what is the effect of transparency? So what if Russia knows we don't consider them a democratic country, so what if Iran knows that the Arab states want to see Iran isolated and neutralized? These are open secrets. Like a sex tape of a man having sex with his wife, they're embarrassing not because they're news but because they're supposed to be kept private. Nobody is surprised that a man has sex with his wife, and nobody is surprised that the Arab states are adversaries of Iran.
If secrecy becomes impossible, as Assange desires, will Arab states stop calling for the U.S. to be aggressive with Iran? Will the United States start believing in Russian democracy? Will American policy wonks stop openly discussing with each other what reasons might persuade the public to support policies that they support for other, less popular reasons?
Well, if every human being on earth suddenly had X-ray vision, would people stop having sex for fear of their neighbors seeing? Of course not. Life goes on.