I wonder if there's any thought of giving Gutenberg a setting ('low', 'medium', 'high') that translates into the level of complexity it will present to the users.

Sort of like how some software has a simple interface but you can switch to "advanced" mode if you want to see all the knobs/dials.

Some users will just want to write, with the editor being as non-intrusive as possible. Other users will want the full Gutenberg experience. I think by going full-bore on this you will at best annoy and at worst lose a significant portion of the legacy customer base.