I feel that there has been a marked lack of communication on when Marionette ends.
Everyone in the game is convinced that it must be going away because for whatever plot reasons, but that isn’t really good enough. For temporary content with achievements and unique rewards, there should be very explicit communication from Anet about when this will no longer be available. I have not been able to easily find any official information on this, and no one in-game has been able to answer satisfactorily.
The wiki article for Origins of Madness states that it ends on February 18, but I have no idea what the source of this is, or if it can be trusted.
All I can easily find is a dev post saying that the secret lair will not be going away with the Escape from Lion’s Arch release, but it says nothing about the Twisted Marionette encounter.
Even with the last release, I had no idea whether or not Marionette would be staying until the Edge of the Mists patch went live, and I could go physically check that it was still around.
Please Anet, make sure to remember to communicate when temporary content ends. I don’t actually care when Marionette goes away in this case, but I do care that we have clear and transparent communication between the playerbase and the developers. I appreciate the new strategy you guys are trying by withholding release pages and keeping things a surprise, but when existing content departs shouldn’t be a surprise. You did a great job with this last year with temporary living story content, but I feel it has been going the wrong direction in the last few weeks.
UPDATE: February 18, 10:00am PST
Rubi made a post about the Escape from Lion’s Arch patch being delayed, and this is the first time I have seen anything by a dev that suggests Marionette will go away.