What is it that would stop Google from turning off access to the Google Play Store by way of Store (Phonesky), especially if MicroG becomes popular?
Google has been known to do this https://moderncrypto.org/mail-archive/messaging/2014/000780....
"As an example, I created a system that randomly generates encrypted JavaScripts that are designed to resist reverse engineering attempts."
If they provide a binary blob that resists reversing, there might not be a way around including that blob.