Disagree that Facebook has been good to every digital publisher. Agree with the trend of traffic increase on both desktop and mobile (has been the trend for a few years now). For those sites that benefit from a lot of social traffic, this does apply:
Virtually every digital publisher has seen two big trends in recent years: Traffic is up sharply, and mobile traffic is up spectacularly, often overtaking the desktop web. In both cases, the cause can be distilled down to a single word: Facebook.
In 2015, then, the winners of the Facebook attention lottery are going to be more videos, as well as genuinely native, in-app content from advertisers. The losers are going to be external websites who have become reliant on the Facebook traffic firehose. That traffic is going to start falling, in 2015, for the first time. And the repercussions are likely to be huge.