Google last week published the schedule for transition to 64-Bit Apps on Android. Starting August 1, 2019, all new apps and app updates that include native code are required to provide 64-bit versions in addition to 32-bit versions when publishing to Google Play. Google Play will continue to accept 32-bit only updates to existing games that use Unity 5.6 or older until August 2021.
Starting August 1, 2021, Google Play will stop serving apps without 64-bit versions on 64-bit capable devices, meaning they will no longer be available in the Play Store on those devices. This will include games built with Unity 5.6 or older.
Vlad Radu, Product Manager, Play and Diana Wong, Product Manager, Android, at Google, anticipate that for most developers, the move to 64-bit should be straightforward. They wrote that many apps are written entirely in non-native code (e.g. the Java programming language or Kotlin) and do not need code changes.
App Developers should inspect the APK or app bundle for native code. You can check for .so files using APK Analyzer. Identify whether they are built from your own code or are imported by an SDK or library. If an app do not have any .so files in the APK, the is already 64-bit compliant.
Google says that Unity only recently began providing 64-bit support in versions 2017.4 and 2018.2, and because of that Google is granting an automatic extension to existing games using versions 5.6 or older until August 2021.