I think it would be tough for Apple to continue selling a lot. We'll see in Q2 this year. Now that more people own these mobile devices, why would they spend money to buy a new one that does the same thing? With the tech available now, there's really no incentive to upgrade, and the only thing attractive is something different from iOS. Also, more people own smartphones with a 2 year contract, and many are switching to Android. I wouldn't count iOS as a competitive advantage - Apple's profit margin is decreasing, which is a sign of that. I believe Android is the more advanced OS, and that is starting to attract people away from iOS. There's still a market for smartphones, but much less people than in 2009-2011, and much more competitive.
Do you think things have radically changed since last quarter when Apple sold the most iPhones it has ever sold and by a substantial margin? I think there is enough incentive to upgrade from, for example, an iPhone 4. Especially when you can get the iPhone 5 at a subsidized price.
And yes Android is going to attract people away from iOS, but at the same time you have more and more people coming into the Smartphone market. Don't discount the fact that new customers are literally getting "made" each year as little Tommy gets big enough to get his first smartphone. And once you get a smartphone it seems you never go back to a feature phone. And you replace your smartphone at least every three years and probably between breaking and losing it much more often than that on average. So no, I'm quite confident that more smartphones will be sold in 2013 than in 2012, just like more were sold in 2012 than 2011.