As far as AppStore is the shortest way from developer to paying customer and iPhone outsells any similar mobile platform (more than 20M iPhones sold vs. 1M of Android phones and <0.5M of Palm Pres) this will continue.
Probably, but I'd expect some part-time developers to defect just to have a better experience. It's not like everyone makes a ton of money on the App Store anyway. It took me significant frustration and annoyance to get my app out, only to have 100 people buy it. If there was a mobile platform that was fun to develop for, I'd switch to it immediately and make stuff there.
I don't know about other developers, but "defect" might be the wrong word. At any given moment, I'm developing for at least 3-5 different platforms, so adding another mobile one, in addition to the iPhone, would make more sense than ditching one for the other.
...maybe it would even help get an app approved faster, if it was a hit on another platform first?
