Some components of FSE will be delivered in WordPress 5.8
Others will come later, in WordPress 5.9 and beyond.
The major things that are missing or need improvement:
- Some blocks need improving for use in the real world;
- Post hierarchical terms,
- Page list
- Post comments
- Some blocks are missing. eg Post-edit
- Really useful patterns
- Custom styling using only Global styles.
- Ability to export theme.json
- Ability to create all template types from the Site Editor
- Out of the box FSE theme import after export.
- Internationalization and localization of templates and template parts.