: I don't think that'll happen... my theory of her continued existence is
: entirely related on the digital nature of the AI, and that we really don't
: know fully what she did or how much of her is implied to be no longer
: existent. Perhaps even knowingly to her. eg if she had copied herself and
: the they don't have knowledge of each other (not that that's what could
: be, just an example). There are a number of plot mechanics that could
: still have her be alive, without being some kind of retcon or tricky
: wording or change or direction or whatever. Really, I feel confident that
: 343 already knows the fate Cortana, so the whole end of Halo 4 would have
: been done that way intentionally - whether she still exists or not.
: But I can't imagine that 343 would get rid of Cortana from Halo in her
: entirety. Not gonna happen. *knock on wood*

None of that is really the driving thing either, at least to me. They had a story about her dying. They had her acknowledge and accept that it was happening, that her life was ending. They showed her die in as clear a way as they could-- she deteriorated and the machinery she was in was destroyed. This all had an emotional weight to it. Having a way out of the situation, even a believable one, doesn't change the fact that we the audience saw her die, and that was the intended take-away, and there were no caveats or exceptions or ways out presented. To undo that would render that story moot. True, that wouldn't make it a worse story in and of itself, and it wouldn't necessarily mean the Chief can't change and grow because that happened, but it would take away a lot of the weight of context, and it would make it feel less purposeful, and it would set a bad precedent.

In other words, any way they bring back the Cortana we know would be "some kind of retcon or tricky wording or change or direction or whatever". I know you're fond of the idea that anything is possible with an AI, but this was explicitly stated to not be possible. To go back on that is to (at least in some way) lie to the audience, and that can work in some cases, but I don't feel this is one of them.