Android is still a carrier driven platform. Verizon has been slamming people into Android phones for a while now. Even when they launched the iPhone they still heavily promoted Android phones in stores. Why? Because they got what they wanted from Google ..control. Google had to create their Nexus lineup so that the carrier crap wasn't there.
It's funny how people on here laud Google. They sold out before they even hit the battle field. I've got zero respect for Google. They want me to bend over and take just like they have.
Note that iOS users don't have to get carrier blessing to update their software and because of that many choose to upgrade quickly.
http://www.cultofmac.com/197280/one-month-later-ios-6-market-share-climbs-beyond-60-report/
There's no chance that Android harms Apple's margins so long as Apple continues to open up retail stores.