The remaining goal posts by the way are where apps get built first and general app quality. The time that developers move to Android after first making their app on iOS is probably shrinking. The disparity of where apps get made first is also probably shrinking.
Another point about why is Android doing so well: Apple seriously needs to get better at services. They are amazing at hardware, they are great at software that runs on devices, but they have bombed again and again on software that runs as a service in the cloud. This severely limits them. Maps, mobile me, icloud syncing, they have trouble keeping their developer portal up, etc. I believe this is a problem with Apple's culture and what they value. Server software isn't pretty, and it's iterative. That is you bring up something that works, then make it better. Apple's culture is to wow with the first try, but they've been disappointing when it comes to software as a service.