I don't expect a Word of God answer, but I do really wonder about how time works in this setting. I mean, Ilya's plans are going to have to revolve around both the idea that he can change the future, and that the scene he saw is impossible to avoid. Is our annihilation, to the point in this rendition of the future, also a certainty? On the other hand, these seem like decidedly different ways of peering into the future. Or rather, peering vs. experiencing. (Then again, can any of the Gods even "see" the future? Surely that would've made the Titans' fight endless or futile. Perhaps my vision is simply a projection based on what Varya knows?)