While there option is always there to produce an add-on, it's "not something we're focused," as their idea behind the Living World lets them do what an expansion would but on a "more regular basis."
Their mad scientist method of achieving this is to form four separate development teams with each given four months to produce two updates deploying across a set period.
“So right now we’re not really looking at expansions as an option,” lead content designer Mike Zadorojny said. “It’s something that’s on the table but it’s not something we’re focused on, because what we want to do is – our idea here is that with Living World, we can do what expansions would have done but do it on a more regular basis.”
“If we do this right,” he added, “we will probably never do an expansion and everything will be going into this Living World strategy.” Each new Living Story update includes new NPCs, new events or instances and is a continuation of the narrative for the game world of Tyria. While technically 'temporary events', they may leave permanent marks.
The first major and permanent update to Guild Wars 2 was The Lost Shores back in November 2012. Then it was Flame and Frost: Prelude in January, followed by Flame and Frost: The Gathering Storm in February. That was eventually followed up by Flame and Frost: The Razing in late March.
It was the deployment of these four teams working on the Living Story updates that led to the chained release of these major updates with Flame and Frost. More recently it produced Secret of Southsun, Dragon Bash and Sky Pirates of Tyria. They want these 'episodes' of content to be regular to draw players back.
Bazaar of the Four Winds launches July 9th with achievements being reworked, and items awarded based on scores accrued through those achieved feats. Below is the official description of the impending update:
"The Bazaar of the Four Winds is gathering— merchants are converging from all corners of Tyria to sell their wares. But this time it’s not just shady characters and risky trades; this year, the mystical, flying Zephyr Sanctum has landed, bringing their magical crystals and amazing movement skills to savvy traders and daring adventurers alike!"
"What a joy it will be to experience the thrill of the trade—and the race. Let’s go!"