The ability to include all the layout info in DBML. Not only table positions but all the diagram metadata (header colors, table group collapsed states,…) in the scope of dbdiagram can also be included in your DBML.
Possible benefits / use cases / scenarios:
- By doing this way, you don’t have to worry about losing the table positions because they will be defined in your DBML, and dbdiagram will look into it to render your tables.
- Diagram cloning capability.
- A prerequisite for the “auto-generate diagrams” feature in the future.
To accomplish this, we intend to revive one of our long-forgotten proposals, the annotation syntax. Here is the detailed proposal: https://github.com/holistics/dbml/issues/53 .
If you want us to support this feature as well, please share your story and vote 
this topic.