Future of Gutenberg Block Editor will be a full-site editing canvas — not just only for post/page content. We’ll be able to manage all site elements with blocks. Primary site’s elements like header, main menu, footer/sidebar widgets area will be accessible within blocks.
Fullsite editing experience should be as simple as possible. Admin menus in the left hand might no longer relevant and should be put to different context only for site’s settings.
In my own humble opinion, default WordPress 5.4’s fullscreen mode when block editor opens would provide a distraction-free canvas. I love this change ❤️