PCDs are traditional PCs and tablets and while this is a slower contraction compared to the previous year, the shipments will decline further by four percent in 2018.

Looking toward the end of the five-year forecast, volumes are expected to continue declining from 423.3 million in 2017 to 393.9 million in 2021. This represents a five-year compound annual growth rate (CAGR) of -2.0 percent, said IDC.

Breaking down the PCD market, traditional PC shipments will fall from 260.2 million units in 2016 to 248.1 million in 2021 units, resulting in a five-year CAGR of -0.9 percent .

Out of the five major product categories in the PCD market, desktops and slates will continue to decline over the duration of the forecast, while detachable tablets, workstations, and notebook PCs will show signs of volume improvement.

Adding in detachable tablets such as the Microsoft Surface Pro, the five-year CAGR improves to +0.3 percent. This is good news, but shows that the overall PCD market is still pretty pants.

More than 69 percent of shipments in emerging markets are going toward traditional notebooks and slate tablets in 2021, and price points remain very sensitive in countries once pegged as ripe for growth.

Convertibles and ultraslim notebooks have found increased favour in developed markets, China will be the only developing market among the top 10 markets for these devices in 2021.

IDC's Quarterly Mobile Device Trackers program vice president Ryan Reith said detachable tablets are expected to see double-digit growth from 2018 through 2021.

"Windows-based detachables already count for close to 50 percent of the volume in this category and this isn't expected to change much over the duration of the forecast. Apple's iPad Pro lineup will remain at 30-35 percent of the category with the remainder going to Google-based devices. It is clear this is a category that has the interest and now investments from both PC and smartphone OEMs, but when looking at the overall PCD market it accounts for just five percent of volume in 2017, growing to 9.4 percent in 2021," he said.