Imagine if that happens, it's gonna be the "wordpress" of community building platforms for future. That's gonna be nutty.
The biggest issue that the developers will face implementing this will be ensuring extensions do not break users current set-ups. A "undo" button will be nice 😛.
I know with SimpleMachines forum software, when an extension was installed, it will give admins a pre-installation error report to say, "You're trying to install this extension however, a 'certain piece of code' is not working and if you choose to continue, it cud break ur forum. If u continue, u need make 'some' code modifications manually."
SMF will then show u wot modifications an admin had to make to ensure an extension wud be operational.
This saved an admin a lot of headache because you could normally tell if an extension will work or not just from a pre-check.
With flarum extensions, u dont know if it will break something until you install it in ur hosting environment.