Multiple sources have now confirmed that the new Haruhi episode, which aired today in Japan, is the first part of the Sighs of Haruhi Suzumiya arc.
WARNING: THE FOLLOWING POST CONTAINS SPOILERS!
For those of you who don’t know, the Sighs arc covers the making of The Adventures of Mikuru Asahina 00. This confirms the predominant fan theory that the “second season” (or re-airing, if you prefer) is merely filling in the chronological holes left by the original Haruhi anime. This all but confirms that Disappearance will not be animated anytime in the near future. Sorry, blushing Yuki fans.
The fan reaction to this news is split. Most are happy that Endless Eight is over and new content is being shown, but some are also irate that Kyoani chose to animate Sighs instead of Disappearance. Many fans are also complaining that the new episodes art quality is poor, sometimes dropping to K-On! levels of failure.
With such wildly varying artistic quality throughout this “second season”, I am personally glad they chose not to animate Disappearance. I would hate to see a good story ruined by bad art.
–Screenshots from Random Curiosity and 4chan