The release date for Drupal 9 is June 3, 2020. But that will not be the only thing being released on that day. Alongside the release of Drupal 9, Drupal 8.9 will also be released on the same day. Drupal 8.9, is a long-term support (LTS) minor release of Drupal 8. The only difference between the Drupal 9 release and the Drupal 8 LTS release will be Drupal 9's updated dependencies and removal of deprecated code. Also good to know is that both Drupal 7 and 8 will be supported by the Drupal community until November 2021.
The Drupal community is working hard on releasing Drupal 9, in fact, a Drupal 9.0.0-beta1 is already available now. This release includes all the dependency updates, updated platform requirements (web server, PHP, and database versions), stable APIs, and features that will ship with Drupal 9. But the stable Drupal 9.0.0 release is as said before scheduled for June 3, 2020.
The end-of-life of Drupal 7 and Drupal 8 is a fact and another fact is, that you want to have a secure and correctly working Drupal platform. So, you need to upgrade to Drupal 9. For now, what you need to do is to make sure you are running on the most recent Drupal platform available. If you are then you only need to make a few small changes to your platform to transfer to Drupal 9. A single project release can now be compatible with Drupal 8 and 9 at the same time, so you don't even need to release a new branch of your project to support Drupal 9.
Drupal 8.9.0 will also be released on June 3, 2020. It will contain the same features as Drupal 9.0.0 while keeping backwards compatibility with Drupal 8. This final minor version of Drupal 8 will receive long-term support, with bug fixes and security coverage until November 2021. Meanwhile, Drupal 9 will continue to receive new features in Drupal 9.1 (out in December 2020) and beyond. But if you are still running on a Drupal 7 platform then the migration to Drupal 9 will be a bit more difficult. Luckily we can help you with this. Want to know more? Contact our Drupal experts.