Event with name same as title of this thread would add content of the scene dynamically to current one. Both events and layout would be added, so it’ll be kinda cross between external layouts and events and as such you could along with looks of the object define behavior of it.
Found a temporary workaround for this and it’s basically to just highlight all events you have and paste it in the new events section of the new scene. As for the objects, you can make a group, then add all the objects you wanna transfer, then copy the group and paste it in the new scene’s object editor 
I meant both at runitme.
You can alrady “load content” of external layout in to the scene in real time and you can also use external events. Maybe can be useful to add feature to be able to load and enable/disable external events in real time so you can activate/deactivate features based on what content (layout) is loaded in to the scene or layouts could have it own events which used when it loaded.
But yeah, something similar to Godot can be useful. In Godot you can load objects and all the object settings and scripts from scene files in real-time using a simple command.
But Godot stores all it scenes in separated XML files and using/store scripts individually for each “node” (object) but every node can have multiple child nodes added so by the end every object (node) that is part of the same node can use the same script but also can have individual script for each.
Imo Godot handle scenes, objects (nodes) and scripts in a very smart and flexible way, maybe worth to copy it