Though there's some reason to be cautious, initial reports suggest that Facebook is on track to shed huge numbers of users this year. As The Huffington Post explains, "according to the social media analytics firm cited in the story, the statistics are merely 'rough estimates'" -- "not primarily intended for journalists, but rather [as] ad estimates for marketers." Nevertheless, the figures, revealed by The Guardian, are too striking to brush aside: In the last month, the world's largest social network has lost 6m US visitors, a 4% fall, according to analysis firm SocialBakers.