The contraction of the PC market continues faster than ever, eaten by the rapid growth of the tablet market, which is expected to outsell laptop and notebook devices for the first time this year and all PCs by 2015. But portable PCs may still be the saving grace for PC sales in the years ahead.

If there is anything new about the news coming out from IDC’s Quarterly PC Tracker, it’s the increase of the rate of the PC’s decline. IDC had initially predicted a decline of “1.3% in 2013 followed by a gradual increase in volume.” Now the analyst firm is predicting a sharper decline of 7.8% in 2013 and 1.2% down in 2014.

2011 may have been the “peak PC” year, when 363 million units shipped. In 2012, 349 million units shipped, with only 321.9 units predicted for the 2013 calendar year. The market is expected to recover a little – by 2017, IDC estimates that 333 million will ship.

These numbers include shipments on both desktop and portable PCs, which is what IDC labels notebook and laptop PCs. That 2017 recovery will have no help from desktop PC sales: shipments are expected to drop from 148 million in 2012 to a predicted 134 million in 2013 and 124 million in 2017: a 16.5% contraction over five years.

Any recovery in the market will fall squarely within the portable PC sector: shipments were 201 million in 2012, and will be down to 187 million this year, but possibly up to 210 million in 2017, which is a net 4.3% uptick for the portable sector.

But where the real growth in portable devices is in the tablet sector. “T]ablet shipments are expected to grow 58.7% year-over-year in 2013 reaching 229.3 million units, up from 144.5 million units last year,” [according to the press release, “IDC now predicts tablet shipments will exceed those of portable PCs this year.

“In addition, IDC expects tablet shipments to outpace the entire PC market (portables and desktops combined) by 2015,” the company reported.

Tablets are not only going to be more prolific, they are going to be smaller. The IDC data is already seeing a sharp decrease in sales of tablets in the 8″-11″ size range, and a healthy increase in tablets with less than 8 inches of screen size. As you can see in the table below, by 2017, 57% of tablets will be in that sub-8″ range.

Worldwide Tablet Market Share by Screen Size Band, 2011 – 2017

The shrinking of tablet size means that a lot less productivity will be getting done on these devices, as smaller tablets are very much consumption devices. This may explain the predicted increase of notebook sales: people will still want portability, but they also will need a platform on which to actually work.

As for the desktop PC, there looks to be no bright future in sight for the once-mighty platform. That which does not move, it seems, dies.

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