Board Thread:Questions and Answers/@comment-39665740-20190601185125/@comment-2202259-20191026002951

From what I understand Ymir Fritz's power transcends all 9 Titans Combined. Perhaps when she died she became the Devil of All Earth. Supposedly her afterlife requires her to create the titan bodies & regenerate Titan Shifters. She seems to choose to kill the Titan Shifters after 13 years for her own personal reasons. It's possible that Eren is going to take Ymir's place once he dies & that he just made the same deal that she did.

Whether the role is called Devil of All Earth, or Source of All Living Matter, it seems to have power surpassing all 9 Titans. Even if someone managed to cannibalize all 9 Shifter Titans, I believe that it's likely they would still need to have the support of this Source/Devil to be able to rival Ymir Fritz. Eren said something about freeing Ymir Fritz from her role, although he's also been getting set up as the villain. Maybe Eren's really going to end up as that Devil?

Mikasa & Armin are necessary in order to stop him from what I understand. While I believe all 9 Titan Shifters will end up in Shiganshina before this is over, I don't think we'll see all 9 of them become 1 shifter. I think it's more likely we'll see the Eldians lose the power of the Titans before this series ends over the following year.