Josh Long/CNET

Windows Phone could be the only major mobile OS to see a gain in market share in the next few years.

Released Wednesday, IDC's Worldwide Quarterly Mobile Phone Tracker forecasts a rise in Windows Phone's global market share from 3.9 percent this year to 7 percent in 2018. That may not seem like a huge leap, but such growth will outshine the market share declines predicted for the other major mobile platforms.

Although it will still dominate the smartphone landscape, Android will see its global market share drop from 78.9 percent this year to 76 percent in 2018, according to IDC. Apple's iOS will maintain second place, though its share is forecast to inch down from 14.9 percent this year to 14.4 in 2018.

Hanging onto fourth place will be BlackBerry with a market share expected to tumble from 1 percent this year to just 0.3 percent four years from now.

IDC

Windows Phone will gain from Nokia's ongoing support as well as that from a lineup of other vendors, IDC said. At this week's Mobile World Congress, Microsoft -- which is in the process of acquiring Nokia's phone division -- announced a number of new Windows Phone partners, including LG, Lenovo, and Foxconn. The next update to Windows Phone will also carry fewer restrictions for device makers, paving the way for more price-conscious products aimed at emerging markets.

But IDC expects the overall smartphone market to become more saturated over the next few years. Growth in worldwide smartphone shipments could drop from 39.2 percent last year to 19.3 percent this year, 8.3 percent in 2017, and 6.2 percent in 2018.

"In North America we see more than 200 million smartphones in active use, not to mention the number of feature phones still being used," IDC program director Ryan Reit said in a statement. "2014 will be an enormous transition year for the smartphone market. Not only will growth decline more than ever before, but the driving forces behind smartphone adoption are changing. New markets for growth bring different rules to play by and 'premium' will not be a major factor in the regions driving overall market growth."