If Apple comes out with new iPhone every year, about half will have the new iPhone and the other half will still be using the old. This ratio will stay the same always since most of people will have 2-year contract and upgrade every two year. Would this be the best scenario for APPLE? (No, I am NOT saying ATT should let everyone have new iPhone at the low price every year.) I am only curious to know how would this half & half scenario work for Apple and app developers.