Good article from Flo about the Android App Bundle requirement and how it seems like Google is making it harder for third party app stores and their fans:
Google Seems to Be Closing the Borders on Its Play Store
To put it simply, Android App Bundles will give Google more power over the apps it hosts in the Play Store. That’s fine for your everyday, run-of-the-mill Android user, who can rest easy knowing their apps are lighter and externally verified through Google. But for folks with a knack for sideloading and going against the grain, so to speak, it’s likely to get annoying, especially if you’re using a third party that doesn’t have the necessary signing keys.