Tablet use continues to grow as globally more people choose slates over desktop computers. According to IDC's most recent numbers, worldwide shipments of tablets are expected to surpass PCs in the fourth quarter of 2013. 

While PCs shipments are still expected to be greater than tablet shipments for the full year, IDC forecasts tablet shipments will surpass total PC shipments on an annual basis by the end of 2015. 

IDC expects smartphones to exceed 1.4 billion units in 2015 and account for 69 percent of all smart connected device shipments worldwide.

In terms of shipment value, the worldwide smart connected device market, which includes PCs, tablets and smartphones, will again exhibit double-digit year-over-year growth of 10.6 percent in 2013, but this growth will gradually slow to just 3.1 percent in 2017. The firm attributes the falling value of shimpents to the increasing impact of low-cost smartphones and the white box tablet market. 

Worldwide smart connected device value is expected to be $622.4 billion in 2013, of which $423.1 billion will come from the sub-$350 smartphone and sub-$350 tablet segments collectively. 

Megha Saini, Research Analyst with IDC's Worldwide Quarterly Smart Connected Device Tracker, said in a statement that low-price tablets and smarpthones will emerge as game-changers.  

"Introducing new handsets and tablet devices at cheaper price points along with special initiatives like trade-in programs from Apple and BestBuy will accelerate the upgrade cycle and expand the total addressable market overnight," Saini said. 

Looking forward, IDC expects the worldwide smart connected device space will continue to surge, with overall shipments surpassing 2 billion units by the end of 2015 with a market value of $735.1 billion. In terms of device mix, total PC shipments accounted for 28.7 percent of the smart connected device market in 2012 while tablets accounted for 11.8 percent and smartphones for 59.5 percent. By 2017, total PCs are expected to drop to 13 percent, while tablets and smartphones will contribute 16.5 percent  and 70.5 percent respectively to the overall market.