IDC says the world will see a billion smartphones shipped by 2015, and that this will be led by Android-powered devices. Meanwhile, IDC also predicts that Microsoft's Windows Phone would come in at second place, but where does that leave the iPhone?

According to the IDC forecast, Android will get a solid 44% of the smartphone market share globally by 2015, which is actually in line with the current smartphone sales trends. Meanwhile, IDC forecasts that Windows Phone will come in at second place, with a 20% market share by 2015, a big leap from its current share of less than 4%.

Apple's iOS, currently the leader in another market -- tablet computers -- will come in at a close third, with a 17% share of the smartphone market. BlackBerry comes in after with about 13%, keeping within close range of its current 14% smartphone market share.

By 2015, IDC says Symbian would be completely out of the picture, noting that top Symbian developer Nokia would have gone all-out with Windows Phone by that time, with its partnership with Microsoft.

Bold Predictions?

Claiming Windows Phone would supplant iPhone might be a radical forecast, but Gartner seems to share IDC's view. It seems the Nokia-Microsoft partnership is expected to pay off, after all. While Windows Phone is currently the mobile industry underdog, strong ties between an able developer ecosystem and a capable hardware maker might just cinch the deal for WP7.

Windows Phone 7/Windows Mobile will benefit from Nokia's support, scope, and breadth within markets where Nokia has historically had a strong presence. Until Nokia begins introducing Windows Phone-powered smartphones in large volumes in 2012, Windows Phone 7/Windows Mobile will only capture a small share of the market as the release of Mango-powered smartphones are not expected to reach the market until late 2011. Nevertheless, assuming that Nokia's transition to Windows Phone goes smoothly, the OS is expected to defend a number 2 rank and more than 20% share in 2015.

It's still a gamble for Nokia and Microsoft, though, and IDC's predictions heavily bank on both companies' release of a viable WP7 smartphone within the year and keeping the momentum through 2015. Otherwise, if IDC just expects current Symbian users to port over to Windows Phone, then that comes with a bit of uncertainty.

At least the forecast Android supremacy is more viable, the way things are going. Manufacturers are reporting record sales figures with Android-powered devices. HTC, which sells both Android and Windows Phone smartphones, more than doubled its monthly sales figure this May, compared with May 2010, and credits this mostly to Android.

But Will It Bake?

These bold predictions have been made in the face of Apple's recent Worldwide Developer Conference, in which Apple's latest and greatest were showcased. The whiz kids from Cupertino just showcased the upcoming iOS 5 and its capabilities, including unified messaging and iCloud. Both IDC's and Gartner's predictions seem to bank on price being the selling point of Android and Windows Phone smartphones. With Android having a presence in smartphones of all sizes and price points, and Windows Phone likely to have a similar product differentiation, this might mean that Apple will find it challenging to overcome the iPhone's image as a premium product.

Still, it's anyone's game. Who knows what Steve Jobs will think of next?