To the surprise of, hopefully, no one:

“Native advertising is going to fuel the growth of digital media, but we may never be able to bucket it out,” said Peter Minnium, head of brand initiatives at IAB, who said nailing down a precise dollar amount is difficult.

Native social advertising is expected to grow from a $1.6 billion market in 2012 to $4.6 billion by 2017, according to research firm BIA/Kelsey.

via ‘Native’ ads to drive digital media growth: report | New York Post.

Much of the growth seems to be coming from more and more publishers introducing more and more products that are meant to attract advertising dollars. Those publishers are seeing sponsored content as a means to offset falling ad revenues elsewhere.