The WordPress core development team builds WordPress! Follow this site for general updates, status reports, and the occasional code debate. There’s lots of ways to contribute:
WordPress 5.4 will be the first major release of 2020 and aims create a block for navigation menus and update Gutenberg to the latest release version as we continue to focus in 2020 on full site editing via Gutenberg. Matt Mullenweg is the Release Lead, Francesca Marano is the Release Coordinator, David Baumwald is the Triage PM, Tammie Lister is the Design Lead, Sergey Biryukov is the Core Tech Lead, Mark Uraine is the Editor Design Lead, Jorge Costa is the Editor Tech Lead, and JB Audras is the Documentation Lead. All release decisions will ultimately be theirs to make and communicate while gathering input from the community. There will NOT be a new bundled theme included in 5.4.
From this point on, no more commits for any new enhancements or feature requests in this release cycle, only bug fixes and inline documentation. Work can continue on enhancements/feature requests not completed and committed by this point, and can be picked up for commit again at the start of the WordPress 5.5 development cycle.
To get involved in WordPress core development, head on over to Trac and pick a 5.4 ticket. Need help? Check out the Core Contributor Handbook. Get your patches done and submitted as soon as possible, then help find people to test the patches and leave feedback on the ticket. Patches for enhancements will not be committed after the dates posted above, so that we can all focus on squashing bugs and deliver the most bug-free WordPress ever.
If you want to dive deeper into 5.4, development is discussed at a weekly meeting in the #core Slack channel and occurs next at Wednesday at 21:00 UTC. Wish us luck!