From our devs:
App bundles is planned as a 4.24 feature, and will let you upload a single file with both 32-bit and 64-bit libraries. Google Play will then repackage and download the correct one on your device.
Starting in August, you’ll need both but you can upload two APK files. 4.23 now has an option to apply an offset to the store version of the APK packaged based on architecture, so you can set armv7 to 0, arm64 to 1, check support for both in Android project settings, and it will make two APKs at once that you can upload. For updates, remember to advance the store version by at least 2 to account for already generating store+1 for arm64 (all APKs uploaded to store must have unique increasing number).
Does that help?