By the power of truth, I, while living, have conquered the universe.
Posted by: annoyinginge
Posted by: HipiO7
Cortana is assumed dead as well as The Didact, but Im positive they are both returning in the next games.
Check the description for the final mission:
"After the death of Cortana..."
Let's look at it this way - there's no way that they're going to imply something meaningfully ambiguous about such an important plot point in a description that is merely meant to be a brief, general description.
In the scene where Cortana binds the Didact with hardlight, one of her copies circles around his head until he is fully bound and then jumps into his helmet - the Didact then falls into slipspace after John incapacitates him with a dud grenade. However slim the chance is, it is entirely possible that a fragment of Cortana still exists now as the Didact's ancilla.