Sword Art Online novel by Reki Kawahara will get a new story arc. The news surprised fans, according to a post in the 18th volume of the novel. Scheduled for 2017, the announcement states: " Kirito will return ."
Therefore, the 18th volume focuses on the sub-arc titled "War of the Underworld" from the "Alicization" arc. In total, the saga included the arcs Aincrad, Fairy Dance, Phantom Bullet, Mother's Rosary, and Alicization.
Finally, the novel will be adapted into an American live-action series , and the film Sword Art Online: Ordinal Scale will be released in Spring 2017.
Via: ANN