The quoted article seems to have a way low estimate: 27 exabyte (27,000 PB) in terms of disk drives isn't that many. Considering that 1TB drives are now rather inexpensive (and even not all that surprising connected to a notebook, as Steve mentions), achieving 27 exabyte only requires 27 million 1TB drives. At $300 per drive, that's only $7.5 billion sales across Seagate, WD, Hitachi et al. (Using more, cheaper, and cheaper-per-byte, smaller drives reduces this number even more -- though smaller faster drives for transaction processing use would raise it.) And $8 billion or so is a tiny fraction of the total private sector IT spend (aggregate of approximately $1 trillion currently).....
What the survey likely fails to consider is that as the cost of storage (gross cost, including drives, ports, footprint, power, people, etc) continues to plummet, the application for it will increase: few organizations stored video/audio in the past, but today many/most do, etc....
Anyway, on a simple back of the envelope basis, seems to me that this estimate is low by a factor of hundreds or thousands!