Board Thread:Questions and Answers/@comment-30882723-20170104074912/@comment-28251580-20170104081418

Volume 18 was the end of the Alicization arc in the Web Novel. Most uf us thought that this would be an end to the main series. But Miki (Kawahara's editor) advised Kawahara to continue the series, thus this phrase was found in v18 and was referring to v19.

Edit: At that point in time, when Volume 18 was released, nothing was known about v19, if it will come, what content will be in there etc. We only had the phrase Kirito will return, which resulted in many theory discussions