Apple purchased Beats Music and Beats Electronics in May of 2014, and the music app that came along with that buy was supported on Android. That makes me think the new Apple Music -- at least the Android version -- will use modified code from the now old Beats Music app.
Ironically, Apple's biggest competitor in the mobile space has dozens of apps for iOS.
You can be a very happy Google apps and services user with an iPhone or iPad, for example with Gmail, Google Maps, Drive, Google Play Music and even with Google Now, which Apple is taking on directly with improvements to Siri and Search in iOS 9.
Will Apple start pushing more apps and services from iOS over to Android?
I'm leery on that one although it could entice some to switch if they like what Apple offers. My suspicion is that Apple Music on Android is a one-off software play, particularly since iOS 8 already added many previous Android-only features to iPhones and iPads; think widgets and more app-to-app sharing with ease.
Either way, it will be interesting to watch and see if this is just a one-time deal to get Apple services on Android phones. And it will be even more interesting to see how many Android users actually take Apple up on its new Music service.