I recently replaced AdMob library with Google Mobile Ads and I have a question about that: Will ads appear on Amazon Kindle Fire devices?
I ask this because I know that Google Mobile Ads depends on Google Play Services, so I'm a little confused.
Google Play Services still supports devices that don't have the Google Play store installed on it. The only difference is that devices without the Play Store (and the accompanied Google Play Services app) on it will not receive automatic updates, so you'll still want to grab new versions of the library provided in Android SDK manager and include them when releasing your app.
As you can see above, if Google Play Services is not installed on the device, it will fall back to the version you included with your app as a library.
https://groups.google.com/forum/#!topic/google-admob-ads-sdk/obflEHgq_og