There are 900 million people with cell phones in China. It is currently and will continue to be the biggest cell phone market on the planet. However, the market's fragmented to little bits; shanzai phone here, nokia there, motorola sprinkled in between. But there are two driving forces common to all of the successful phones in China.
1) Price 2) Adaptation to local needs
Shanzai (unbranded local phones) came out and took massive market share by having an almost immediate feedback loop with which to respond to customer demand. Want two sim chips? You got it. Want a phone so loud it turns into a boom box? We can do that. Can you imagine Steve Jobs making these concessions?
MediaTek is cranking out Android capable SoC that bring the price of a smartphone down to $150 - unsubsidized. This is a price level that allows Android to go Shanzai - a very scary proposition for any large handset player. What now separates these 'low end' phones from the high end? They're not perfectly designed by Jonathan Ive, they're not super intuitive, they're not 4g, but they're good enough for China. Remember how Flip came out and just decimated traditional video recorders? It was good enough. MediaTek's $150 android phones are good enough.
If you really want to put the nail in the coffin, realize that if they're good enough for China, they're probably good enough for Africa, for South America, and beyond. The iPhone might retain the high end crown, but Android will undoubtedly become the dominant global smartphone platform.