NPD, market research firm, suggests that Apple’s tablet market share will drop to just over 50 percent by 2017. Android and Windows-based devices will, obviously, have a hand in it, and, as NPD expects, will begin continue to eat into the iPad's overwhelming lead by 2014.
The overall tablet market will swell from 81.6 million units in 2011 to 424.9 million units by 2017, and tablet shipments will surpass those of notebooks by 2016.