User blog:Alpatron/Brand New Made in Abyss Anime Sequel Beyond the Third Movie Announced

The official Made in Abyss Twitter account announced the decision to produce a new sequel to the Made in Abyss anime, which probably will follow the story after the third movie, Dawn of the Deep Soul. It's not been said which form the sequel will take—it could be another movie, another season, or even one or more OVAs. Alongside the announcement, the Twitter account showed a colored propagation picture of the entrance to the sixth layer, originally from the manga.

This is all of the information which has yet been shared.