Google announced in their Android Developers Blog that new and updated apps which will be coming to Play Store from mid 2018, i.e. from August next year must be following certain standards. Google has taken this step to improve security, performance and reduce fragmentation in Android apps.
New apps hitting Play Store from mid next year should at least target API level 26 (Android 8.0 Oreo), however the newest one as of now is 27 (Android 8.1). And from November 2018, updates to the old apps also must target API level 26 or 27. But, if an app is not updated in a long time, then there is no need for it. Google also said that with every new releases of Android, the apps should also target those newer API levels. That means, when Android P goes official next year, developers will have to update their apps to newer API level.
64-bit support was added to Android in 5.0 Lollipop. Google says that currently over 40% of Android smartphones have 64-bit support. Apps that support native code are based on 32-bit only. But, Google says that even though 32-bit apps can run on 64-bit hardware but the actual performance is hindered. Thus, from August 2019, all the apps should have 64-bit versions along with their 32-bit counterparts. Also, the developers can include both the libraries in a single APK.
From early next year, Google will be adding metadata to every apps for additional security and ensure that an app is officially distributed by Google Play. Developers doesn’t need to do anything, this will be done by Google.
Google announced these new things earlier, so that developers could start working on it. So, if you are a developer you should probably look into it.