I'm curious how often this has actually occurred in the App Store? I can't think of too many apps that Apple has released that have many competitors. Sure, there are the built in apps (which you can remove) but I certainly haven't seen any lack of To Do or weather apps on the App Store.
It's an issue for Spotify vs Apple Music for instance. Apple wants a cut of Spotify's fee, and also had APIs for Apple Watch etc only they themselves could use.
