Based on a greater decline in demand than predicted in the first quarter and concerns that tablets and 2-in-1s will face additional market challenges, research firm has lowered its 2014 sales projections. The research firm forecasts that worldwide tablet plus 2-in-1 will reach 245.4 million units, down from the previous forecast of 260.9 million units. The new forecast represents a 12.1% year-over-year growth rate, which is notably lower than the 51.8% year-over-year growth of 2013.

"Two major issues are causing the tablet market to slow down. First, consumers are keeping their tablets, especially higher-cost models from major vendors, far longer than originally anticipated. And when they do buy a new one they are often passing their existing tablet off to another member of the family," said Tom Mainelli, Program Vice President, Devices & Displays at IDC. "Second, the rise of phablets - smartphones with 5.5-inch and larger screens - are causing many people to second-guess tablet purchases as the larger screens on these phones are often adequate for tasks once reserved for tablets."

As large phones clearly impact near-term tablet growth, IDC expects the market to rebound by shifting its focus back toward larger-screened devices. Products with larger screens--like Microsoft's new 2-in-1, the 12-inch Surface Pro 3 -- are expected to play a greater role in the market going forward.