There was also a slowdown in 2014 in tablet shipments, which "drives the notion that PCs still play a key role for consumers and businesses," Mainelli said. Gartner and IDC both noted the tablet growth slowdown in October, but by late November, IDC said that tablet shipments would rise by 7.2% in 2014 -- reaching 235.7 million units -- compared to 52.5% in 2013.
The main reason for the tablet slowdown is that users are holding on to tablets longer, plus more users are taking advantage of full-fledged applications on PCs, rather than tablets.
Mainelli has also said there are ongoing questions about the longevity of the tablet form factor, which led some buyers to turn to desktops and notebooks. For businesses, PCs have been aging, with many running the expired Windows XP, but they are now being forced to upgrade their computers.
Another factor in the mix is the explosive growth in large-screen smartphones, sometimes called phablets, that have a 5.5-in. diagonal display, such as the iPhone 6 Plus, or even larger models.
"PCs still have a big role to play, primarily in commercial but also in consumers' lives," Mainelli concluded.
Gartner's Baker said tablet sales will be strongest in emerging economies, such as India. Sales will be less in the U.S. and other developed economies, where users find that a tablet that's multiple generations old can still do the job effectively.
Even if tablets and smartphones do get used more than half the time ahead of laptops and desktops for online work, as Gartner predicted, there's still going to be a variance in how workplaces and individuals approach the question.
"Remember, this is a personal preference," said Gartner analyst Ken Dulaney in an email. "Some people want one system to do many things. Others insist on many computers working as one."
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