According to InformationWeek, by the year 2015, assuming we aren't killed in the 2012 apocalypse, the Windows Phone 7 will overtake Apple's iPhone. Now this doesn't mean that the WP 7 will be in first; Google's Android phones are projected to blow away the competition with a 45% market share, with Windows in second at 20%. Apple's iPhone and its iOS system will have roughly the same market share they currently own at just over 15%. The presumed increase will come as the IDC surmises that Symbian owners, who represent just over 20% of the market today compared to WP 7's 5%, will happily convert to the Windows platform, leading to Symbian's demise.
Android is poised to take over this year as more and more popular phone's utilize its operating system. It's predicted to ascend to 40% market share this year, so the projected figures aren't that crazy. It's just Microsoft's market expanding that much seems ridiculous at this point. The sales have been underwhelming and updates have been botched so unless they increase the quality and service of their phone, it's going to go the same direction that the iPod killing Zune went. There's a reason it's not taking over at this moment and besides an assumption that Symbian will fall down, there's no reason to assume Microsoft's phone will take over. Most people will probably go to Android as it continues its takeover from the biggest and most user friendly company, Google. Apple and Google specialize in service while Microsoft botches updates. Which would you choose?