When does Sword Art Online return?

Sword Art Online is a Japanese light novel series written by Reki Kawahara and illustrated by abec. The series takes place in the 2020s and focuses on protagonists Kazuto "Kirito" Kirigaya and Asuna Yuuki as they play through various virtual reality MMORPG worlds. The novels and the manga adaptations have been licensed for release in North America by Yen Press. Six video games have been released for multiple consoles.