Following last year's Sword Art Online the Movie: Ordinal Scale film and the upcoming spinoff, Sword Art Online Alternative: Gun Gale Online, A-1 Pictures will return with a third anime season in the main SAO anime series which covers the Alicization arc (volume 9 thru 18) of the light novel from Reki Kawahara.
The Asterisk Wars' Manabu Ono will be directing the upcoming season. Fans of the light novel series have been excited for the Alicization arc to be depicted in anime form as the new main character appearing will be a guy instead of another girl that ultimately ends up joining Kirito's harem.
The video confirms that the third season will premiere during the Fall 2018 anime season in October.