Starting next month, app bundles will be the default means of distributing Android apps in the Play Store. It’s a way to dramatically reduce download size for apps that target different hardware and build in extra assets without taking up extra space. App bundles are coming to Amazon’s branded Appstore, too. Someday.

In a new post dated July 16th, the Appstore Blog told developers that Amazon will begin supporting the app bundling process… but pointedly fails to give any kind of timeline for when implementation will be available. That’s going to create a small headache, as it’s one more difference between developers’ processes for submitting apps to both Google and Amazon.

On the plus side, Amazon says that when app bundle support is added it will be entirely optional, so those who aren’t onboard with the new format won’t need to make any changes. According to the post, the signing and submission process will not change, and there is an existing “roadmap” for app bundle support rollout. Amazon says it’ll share its plans when the actual changeover gets closer.