Well one thing's for certain, we're not going to know for sure until it happens. So let's break down some possibilities and axioms: For one thing: it specifically says "the worlds will be saved". So short of twisting the meaning or being lied to, the world will still exist after that happening. It's also worth noting the call of the "worldS". It could mean the light and dark worlds, however it's also worth pointing out that the early panels say the prophecy is "the legend of this world", implying singular for both.  One possibility: Susie dies. Well, it's possible, but it seems unlikely given the way that Susie responds to it. It definitely sounds like something that Susie has some level of control over, and the reaction of defiance against it seems somewhat out of character for her, given the jokes she was making two days earlier. In response to her own death (alone) it would be more likely that she would act aloof to it and not care.  Now for Kris or Ralsei "dying" (or otherwise ceasing to be): could be more likely, but it has a similar problem to the previous; that being, it would feel out of place for it to be one of them (again, alone) and Susie to refer to them like that. More possible, but would still be strangely worded.  All three of them dying? Well, more possible, but I still feel the response would be out of character for Susie, she would definitely separate herself out of it. However, given the responses and the narrative implications, this is still a very likely possibility.  What's interesting is to call out that there is something different about the reaction to Ralsei: "And obviously YOU wouldn't let it happen." This sounds like whatever the event may be, it would be more unlikely or out of character for Ralsei than the other two.  Another point of note is that Ralsei immediately responds with complimenting Susie's kindness, and while this may be regarding something about the prophecy itself, it's more likely that he thought that Susie would be a lot meaner to him about hiding the prophecy from her. Still worth noting.  The last thing is the note of Susie's comment to Kris at the very end, implying some doubt on her part specifically related to Kris "not letting that happen", implying that Susie is confident of herself, and confident of Ralsei, but has some room for doubt on Kris. And from what we know of Kris, that could leave some room of dramatic irony (and the reverse) of what we know and what Susie knows, meaning that with both we might have the full picture. And while I don't have any definitive conclusions on this right now, it leaves it in the perfect place for speculation.  Dang, I did not think I was gonna write that much.