Apple are highly unlikely to put out an API for other to use as they wish like Google did.
That is 100% wrong.
The strongest reason I see for Apple to replace Google with their own mapping solution is in fact to give iOS developers an API they can "use as they wish".
The current Google Maps API is rife with restrictions. Have to watch the geocoding load from your app or it will be shut down. Can't overlay turn-by-turn instructions (what? You thought that restriction, meant to drive you to back to Google Maps, came from Apple?)
Apple having their own mapping system means NO restrictions on developers, or at least ones directly related to load only and not the protection of Google revenue streams...
At the end of the day if it's only available on iOS and Mac then it's essentially on a minority of devices on what is now a minority platform.
There are still more iOS devices than Android devices overall.
Especially in the U.S. Here's a conundrum for you. Sprint & AT&T and Verizon have all said the iPhone is leading smartphone sales, usually by a good margin.
So how exactly would Android have more units sold in the U.S. if that continues to be true?