Sword Art Online brought the huge Alicization saga to an end with the War of Underworld arc's final episode, but the series ended with a major tease that Kirito will be returning to the anime soon. The War of Underworld's final episode introduced just as many questions about the future of the series as it dealt with concluding, and the final moments of the series saw Kirito, Asuna, and Alice entering an Underworld that has advanced 200 years from the last time any of them had set eyes on it (for as far as Kirito and Asuna remember).
The series even ended with a tease of a major story to come in the future (one that has not even revealed itself in Reki Kawahara's original light novel series), and the final moments of the episode saw Kirito looking backward and opening a door to the future with the words "Kirito Will Return." This tease was actually illustrated in those original light novels, so it's definitely something special. You can see the comparison between the two as gathered by @Black_IDKirito on Twitter:
「ソードアート・オンライン -アリシゼーション-」を最後まで見てくれた皆んな、本当にありがとう！ステイ・クール。September 19, 2020
Kirito will indeed be returning to anime soon, but not as a continuation of the mainline Sword Art Online story. Instead, we will be getting a new adaptation of the spin-off novel series written by Kawahara, Sword Art Online Progressive, that serves as a remake of the first moments in the Aincrad arc. Filling in the gap initially skipped over in the original telling of the series, this story sees Kirito and Asuna take on the Aincrad floors at a much slower pace. So fans wanting to see Kirito (but not necessarily God Kirito in Alicization) will get their fix with this series!
Would you want to see Kirito make his return in a new Sword Art Online anime someday? Will you be checking out Sword Art Online Progressive, or are you hoping to see what's after Alicization? What are some of your favorite Kirito moments from Sword Art Online: Alicization overall? Let us know your thoughts in the comments or you can even reach out to me directly about all things animated and other cool stuff @Valdezology on Twitter!