While I've used WordPress in many ways over the last nearly ten years, I primarily spend my time working on two publications: Scary Mommy and Cafe. "Big Media" publications have challenges and use cases that are different than standard WordPress sites. As Gutenberg continues to evolve, there are a number of use cases that I see as needing to be accommodated. Most of these are things that don't need to be solved "out of the box", but that the extensibility of Gutenberg should accommodate.
It's possible that some of these use cases are already accounted for, but that that the documentation on them is lacking.
Before "Publish" can be pressed, a number of steps need to happen. This could be selecting a featured image, making sure some taxonomies are properly filled out, or that there is 2nd sign off. This takes the form from the super basic such as what make.wordpress.org sites use ( an "Are You Sure" checkbox that must be checked before the publish button is enabled) to the complex custom plugins that are prevalent.
The important part is that there needs to be a documented and extensible way of only allowing posts to be published when other criteria have been met.
Out of the box, Gutenberg has alot of blocks. Not every site needs a "Verse" block, and there needs to be a way to remove it. As the classic saying goes, "Design is done not when there is nothing left to add, but instead when there is nothing left to take away". The ability to remove blocks is necessary for the success of Gutenberg.
Currently, the headings block in Gutenberg allows for selecting H2, H3, and H4. What about sites that also support H5? What about sites that only use H2? There is a need to make minor modifications to many of the default blocks. While some sites and some users benefit from allowing the content producer to select the alignment of blocks, other sites have strict rules and want to lock it down.
There is a need for blocks such as subheads that only exist after the title. Similarly, there may be editorial rules such as never using more than 3 twitter embeds, or always having at least two paragraphs between headings. These should be a way to enforce these rules.
As Gutenberg continues to evolve, more modification requirements are sure to come up. It's going to take years before all sites can use Gutenberg due to the millions of dollars invested in custom editorial processes, but these are my initial modification use cases. What are yours?