Not sure how Fox becoming mainstream relates to the rise of the Samizdat in the Soviet Union.  In any event Breitbart, like Fox has exhausted the cesspool as source of funding and readership.  One can only wonder where its former readers have gone. 
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Breitbart News seems to be cleaning house after readers and advertisers drift away
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https://www.washingtonpost.com/lifestyle/style/is-breitbart-news-veering-away-from-the-farthest-far-right/2017/06/06/35f91160-4ad1-11e7-a186-60c031eab644_story.html?utm_term=.567bf68364d7&wpisrc=nl_evening&wpmm=1