IMO, very soon the large number of apps for Apple's devices will become a deterrent for developers. For example, imagine the following situation: Android phones gradually take over in popularity (signs of this are already here), however there are still fewer apps for Android. A developer can reach at least as many potential customers if coding for Android, however the new app will have to compete with many more pre-existing apps at the Apple store, and will be likely to be lost in the crowd. So it would make more sense to code for Android first (or exclusively).

What I expect will happen eventually is that, as soon as certain core functionalities are provided by a few hundred apps, any additional fluff will not matter. People will get tired of it, and app stores will lose their current appeal, remaining a useful necessity but without the fierce competition we witness today.