A new report by Gartner claims that the Windows 10 upgrade bump is already over and that PC sales will all again in 2020. This corresponds roughly with my own expectations for PC sales, which I feel have essentially plateaued after several down years.

“Even after experiencing a return to growth in 2019, PC shipments are still forecast to decline in 2020 and beyond,” Gartner writes in its latest report, which also concerns other personal computing devices, such as smartphones. “Gartner estimates that one billion PCs will have migrated to Windows 10 through 2020 — around 80 percent of all PCs in use.”

That number is interesting because it means that Gartner believes that there are only 1.25 billion PCs in use worldwide. Microsoft’s latest figure for the active PC market, which hasn’t been updated recently, is 1.5 billion. But I suppose that makes sense: With PC sales settling at a new lower level each year, it stands to reason that the installed base would contract over time as well.

“The PC market’s future is unpredictable because there will not be a Windows 11,” Gartner research senior director Ranjit Atwal said. “Instead, Windows 10 will be upgraded systematically through regular updates. As a result, peaks in PC hardware upgrade cycles driven by an entire Windows OS upgrade will end.”

Gartner says that PC sales will fall to 251 million units in 2020, a decline of 3.8 percent from the 261 million it shipped in 2019. (I combine and average data from both Gartner and IDC in my own market share analysis.) And then they will fall again, to 247 million units in 2021 and then 242 million units in 2022. Assuming this is even vaguely accurate—they’re just predictions—that will represent roughly seven years of flat or slightly down sales overall.

As for the overall personal computing, Gartner says it expects device sales overall to decline slightly over the next three years, with total unit sales hitting 2.166 billion in 2020, 2.153 billion in 2021, and 2.31 billion units in 2022. Mobile phones, in particular, will remain relatively steady, hitting about 1.7 billion in each of those three years.

Gartner further estimates that 5G smartphones will account for 12 percent of all mobile phone shipments in 2020, and that will they will hit 43 percent by 2022.

“From 2020, Gartner expects an increase in 5G phone adoption as prices decrease, 5G service coverage increases and users have better experiences with 5G phones,” Mr. Atwal said. “The market will experience a further increase in 2023, when 5G handsets will account for over 50 percent of the mobile phones shipped.”