As an owner of both Android and iPhone currently, I believe that Android could surpass iPhone based on its customizable features. If the iPhone had more options to customize easily, it would probably remain at the top of the phone world. I enjoy both operating systems for their own strengths, but I feel Android has the ability to get ahead.
Android has less boundaries associated with it than the iPhone does, which is great. They have apps that iPhone can't download which I find great. They also have many phones that have similarities to the iPhone, but have things that have been improved to work better than the iPhones' internal software. iPhone had too many problems for me, so I switched back to Android.
Over the past number of years, iPhone has become the plaything of the rich while Android has appealed to the masses. Very few buyers, other than the tech geeks and those with money to burn, will buy new iPhone and Apple products. The rest of us will go with the cheaper, more accessible platform which is Android.
I do not think that the Android will surpass iPhone phone. They are both very popular and new technology products. I do however think that the iPhone is more popular and well known name brand. I again do not think that the Android will surpass it but it may be about equal.