The first and most important part of this story is it’s very likely it doesn’t affect you. If you have a device from a major OEM who legitimately ships Google Play Services enabled devices you’re fine. However, if your device has not been certified for Play Services, eg you sideloaded Google apps, you might be in trouble.
According to code found in the APK the Google Messages app may be about to start warning users on uncertified devices that “On March 31, Messages will stop working on uncertified devices, including this one”. So what is an uncertified device?
Simply put uncertified devices are those that have either not applied for, been rejected or are ineligible for Google certification of the handset. Without certification, device makers can not ship Google Play Service, and without that, most Google apps will work, however, Messages doesn’t need Play Services.
Up until now it was possible, but not always easy to sideload Play Services and still get the full Google Android experience, but Google has begun to clamp down on sideloading on non certified devices, and may soon start stopping Google Messages from working as well.
Why? It’s thought to be security-related. With end-to-end encryption rolling out Google can not validate that non-certified devices are secure and that the messages would remain protected. As such they seem to be making the move to stop these uncertified devices from even using the app. We shall see how this plays out.