iPad to account for one third of all tablet sales by 2016, says research firm

A new report from Forrester Research says that sales of tablet devices are expected to hit over 375 million in 2016, resulting in over 670 million in use worldwide. Considering that there were 56 million tablets purchased worldwide in 2011, that's a compound annual-growth rate of 46 percent.

This could spell some major disruptions in the PC market, but Forrester remains confident that the two markets will complement each other, rather than tablets cannibalizing PCs. Still though, tablets will eventually "become our primary computing device," says analyst Frank Gillett.

"Our casual estimate is that there will be 2 billion PCs in use by 2016, despite growing tablet sales," said Gillett in a blog post. "That's because tablets only partially cannibalize PCs. Eventually tablets will slow laptop sales but increase sales of desktop PCs. That's because many people, especially information workers, will still need conventional PCs for any intensely creative work at a desk that requires a large display or significant processing power."

Apple's market leading iPad is expected to account for a third of all tablet purchases by 2016. Forrester also estimates that Google's Android operating system will decline in market share, partially thanks to the launch of Microsoft Windows 8; Forrester believes it'll be a couple years before Windows tablets really make a dent, however.

To hint at where growth is taking place, the study finds that 40 percent of sales are going to push into emerging markets, while just over a third will be business-furnishing needs.