Update 13 is scheduled for August 9th, and the update will conclude the Azimuth Saga story and set the stage for the next major chapter. Since the story has been running since October 2020, and the Odyssey expansion came out and added new features since then, special considerations are being taken for this finale.
“Horizons and Odyssey currently exist as separate versions of the game: 3.8 and 4.0. The latter contains the foundational code which supports Odyssey content and a multitude of improvements added since Odyssey’s launch while the former does not….
To allow as many players as possible to experience the new narrative and gameplay elements, we intend to give all PC players access to version 4.0, at no additional cost, while keeping the upgrade to Odyssey optional. You will still be able to launch Elite in version 3.8 if you choose. This option is expected to come in the weeks following Update 13 with more details to be shared closer to the time.”
This means that all PC players, including those who never upgraded to Odyssey, should be able to experience the story, as well as a variety of features, but Odyssey players on 4.0 will be able to have the full experience. 4.0 will be unlocked permanently for all PC players, and they will have access to narrative content even if they don't have all the upgrades from Odyssey.
With Elite Dangerous moving to a PC-only future, ending console updates back in March, the team at Frontier plans to let console players migrate their accounts to PC soon. Those who are able to do this will also be able to access the new content and keep the 4.0 access.