Possible Guild Wars 2 expansion Heart of Thorns trademarked

UPDATE 23RD JANUARY: Whatever Heart of Thorns is, and I suspect it's an expansion, will probably be announced during the Guild Wars 2 PAX South bonanza tomorrow - conference is a such boring word. This kicks off 4.30PM GMT and you can watch it via the embedded Twitch stream below.

Coinciding with the news is a sale - pick up Guild Wars 2 for $10 this weekend (75 per cent off). The offer goes live tomorrow at 4pm GMT, and copies (downloadable) are sold directly through the Guild Wars 2 website.

ORIGINAL STORY 13TH JANUARY: Looks like a first full Guild Wars 2 expansion may be on the way - NCSoft has trademarked (via Reddit) Guild Wars 2: Heart of Thorns.

There's no content detail yet but game developer ArenaNet has an announcement primed for PAX South, Saturday 24th January, starting 4.30pm GMT and lasting until 6pm GMT.

From the PAX South site: "Join ArenaNet president and co-founder Mike O'Brien and Guild Wars 2 game director Colin Johanson for an exclusive sneak peek at what's next in Guild Wars 2 and be among the first to hear how we're setting up a new framework for how an MMO can grow its universe. The Living World was just the beginning."

There's a logo:

Guild Wars 1 had a handful of expansions but so far Guild Wars 2 has relied on regular content drops via a Living World plan to enlarge the game, as well as the occasional bumper feature patch.

What could an expansion bring? New professions/classes? New areas? Big new gameplay features? What would you like?