Wow, really cool article!
I am not a huge fan of front-end dev, so I am really excited about the great opportunities behind this work/research. It will be another major step in the democratization of UI and less work at maintaining the web views.
My biggest concern is the model capacity. My question is: in your opinion, will it be able to handle very long HTML page? not to mention when it will be added a lot of CSS or JS. Even with more layers, will the model be able to generate corrected syntax(for really long pages)? will it need some additional modules(not only layers) to handle this? maybe a different problem formulation?