While Apple dominates the tablet market today, the iPad's share of the as lower-priced competitors like the arrive.

Apple shipped 15.4 million iPads in the fourth quarter of 2011, up from 11.1 million in the third quarter. The company had 54.7 percent of the worldwide tablet market in Q4, down from 61.5 percent in Q3, the IDC says.

Android's share is rising, largely at the expense of the iPad, which runs Apple's iOS mobile operating system.

"As the sole vendor shipping iOS products, Apple will remain dominant in terms of worldwide vendor unit shipments," said Mainelli. "However, the sheer number of vendors shipping low-priced, Android-based tablets means that Google's OS will overtake Apple's in terms of worldwide market share by 2015."

There's one very bright spot for Apple, however. IDC predicts that iOS will remain the market leader, revenue-wise, through 2016 and beyond.