Drupal 9 release date has been pinned for June 3, 2020, and it's coming up super fast. What does that mean for your site?
First of all, don't panic. Drupal 7 and 8 end of life are scheduled until November 2021, so there is plenty of time to upgrade. However it is always good to plan ahead with time and take advantage of the new features and security releases with the new version.
If you are on D7
Moving to Drupal 9 will be very similar as moving to Drupal 8, and in fact, there is no reason to wait, and the recommendation is to move to D8 as soon as possible, incorporating the tools described in the next section to search for possible incompatibilities.