The expected increase in Windows phone shipments will not be enough to make up the difference.
Windows wasn't the only platform that Gartner said would grow slower than it had believed before: Apple's iOS and OS X combined number were also downgraded.
For 2014 and 2015, Gartner now forecasts that iOS/OS X will power 271.1 million devices in 2014 — most of them iPhones — and 301.3 million in 2015, for year-over-year growth rates of 14.8% and 11.2%.
Six months ago, Apple's estimated shipments were more optimistic: 344.2 million and 397.7 million for this year and next, respectively, representing increases of 29% and 15.4%.
Not surprisingly, Android will take up the slack, said Gartner, which predicted Google's mobile operating system will become even more dominant. Where six months ago Gartner projected that Android device shipments would grow by 25.6% and 13.8% in 2014 and 2015, today it modified those estimates to 30% and 17.3%, respectively.
This year and next, Android will account for 48% and 52.9% of all device shipments, Gartner forecast today, upgrades from January's numbers of 44.6% and 44.7%.
Gartner is now pegging total Android device shipments for 2014 and 2015 at 1.17 billion and 1.37 billion, up from previous bets of 1.1 billion and 1.25 billion.
Shipments of Windows-powered devices — personal computers, tablets, hybrids and smartphones — will boast even larger leads over those that rely on Apple's iOS and OS X, Gartner said in a revision of an earlier forecast. (Data: Gartner.)
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