Google Play Services is dropping support for Android Jelly Bean
Android is often criticized for its fragmentation, but that situation also has a rather interesting side effect. Even while manufacturers have abandoned very old devices, Google has maintained support for versions of Android going back almost a decade, as long as there are still enough users to justify the maintenance cost. It seems, however, that the death knell has tolled for Android Jelly Bean as Google announces the discontinuation of Google Play Services support for devices still running on the 2012 Android release.
Android Jelly Bean holds the distinction of having more than one Android release under the same name, namely Android 4.1 to 4.3. This was back in a time when Android was still in a state of rapid development and flux, and releases didn't seem to follow a reliable cadence just yet. It was a pretty big release, too, introducing a refined Holo UI and many changes under the hood, like support for Bluetooth Low Energy.
Google reveals that Android 4.1 through 4.3 together now make up less than 1% of the active devices, giving it the freedom to drop support for these Android API levels (16 to 18, respectively). It might surprise some to hear that Google Play Services actually still supports these devices, and that's thanks to Android's modular nature. The proprietary Google Play Services exists separately from the open source Android platform, and Google can maintain support for older devices separately, usually through compatibility libraries.
Of course, nothing lasts forever, and Google says that it is dropping support for those devices running Android Jelly Bean, starting with a new Google Play Services to be released in August. That doesn't mean those devices will stop working immediately, but they might see certain things starting to break, especially those that rely on Google Play Services. There is a possibility they might not be able to use Google Play Store eventually as well.
App developers are advised to use Android API level 19, a.k.a. Android 4.4 KitKat, as the minimum target version for their apps. That means, however, those apps that will be updated to that will no longer be visible or installable on devices still running Jelly Bean. Developers do have an option to still spin out an APK targeting these deprecated versions, but Google hopes that everyone will just upgrade to a supported Android version instead.