Using Bubble as an example i think opening up a plugin system is what is going to make dropsource a very powerful tool and change how mobile apps are created.
Anytime i think about a plugin system the Apple App Store and Google play store comes to mind. Imagine apps could only be created by Apple or Google themselves.
Once they created an SDK for creating apps on their different platforms, this opened unlimitless possibilities.
When i thought about a plugin system in Dropsource i was thinking in terms for example Android plugins (https://developer.android.com/studio/projects/android-library.html) where Developers could take some existing Android libraries/plugins (or create their own) (see examples here https://medium.freecodecamp.org/25-new-android-libraries-which-you-definitely-want-to-try-at-the-beginning-of-2017-45878d5408c0) and use whatever mechanisms Dropsource provide to define the the library properties and hook into a dropsource application.
Waiting to here more.