The story that launches today will continue over the next three major releases (roughly one major release per quarter), joined by system updates, additional rewards, new weapon proficiencies, new instanced combat encounters, and more. This new model is meant to ensure that the next major story and content update is never more than a few months away and that the game is supported with a regular cadence of content.
We’ve already started applying lessons from the development of Guild Wars 2: Secrets of the Obscure to our fifth expansion, which we expect to be released next year.
https://www.guildwars2.com/en/news/guild-wars-2-secrets-of-the-obscure-launches-today/