Yes, much of this is my opinion. I don't think it's up to opinion what the story is about unless you subscribe to a particularly strong strain of "the author is dead", in which case you can say it's about anything.
Also, I've been meaning to mention, Cortana said they might pair him with another AI similar to her-- that could easily happen and she could take up that role, and there could be a whole exploration of that, and that could fill the necessary holes, mainly gameplay and in-mission dialogue. It would not fill the hole of Cortana as a character-- or at least it shouldn't, that would be another misstep-- because nothing should.

: I disagree that just because it's not in the game it can't happen in the
: game. On the contrary, if you only take in the game's story, you may more
: easily swallow the plot 'trick', so that when established extended
: knowledge (speaking in general here) is incorporated into the game it can
: be that much 'cooler' (if done well). The very nature of the Smart AI
: leaves open unknown possibilities about how an AI might possibly continue
: to exist beyond the 'expected norm'. For one, Cortana being a unique
: entity; Forerunner technological 'space magic' influence (as unpalettable
: as that is to some people); satellite narratives implying more complexity
: than we can grasp (eg ILB); plus, IMO, storytelling mechanics and styles
: that fit this dynamic to a T; etc.

Cortana coming back would not be "cooler" than the alternative. I don't see how not knowing about whatever magical thing they bring in in advance would actually be better than knowing about it and accepting it ahead of time.
Forerunner space magic is unpalatable because it's a plot device, it exists to make other parts of the story function.

: Chief holding the chip. We don't know why, or what it actually contains if anything.

I meant plot stuff before she died.

: Cortana's very 'special' nature. What that means for a Smart AI, if anything.
: Comments about finding Halsey to seek a solution to this growing rampancy at
: 7 years.
: The fact that Cortana's essentially the most powerful human AI; loves John;
: seems to be striving to be more human; yet still succumbs to that 7 year
: soft limit?

Yes, she does, because some things you can't fight.

: Does not seem right that she would gone for good as of Halo 4 of 6. etc

Why does it not seem right?

: Yes, as I previously exampled. I never said that wasn't true.

: Regardless of whether 4,5,6 is another trilogy, it's pretty clear they will
: be going to 6. That's still 2 games, trilogy or not. And Halo 1-4 have
: always so far centered around John and Cortana, with occasional dabbling
: with other characters. The center has always been John and Cortana though.

You admitted elsewhere it hasn't always been about that, so which is it?

: To you, it seems.

If it wasn't about her dying then what was it about?

: For now :P

: Apparently, as witnessed by John :P

: To the best of his knowledge :P

: Which is why she'll return :P

: Of course not :P

Why are you using smilies as punctuation? It's getting really, really annoying.

: The end of Halo 6, Master Chief narratives; no more Chief or Cortana
: stories. :P

They're not going to do that any time soon-- not because of the story, but because of money. They know people like you will swallow whatever plot device they cook up so they can get more of the characters they like.

: No, there was character dialogue based around their observation and
: perception of events that were being presented to us in a game cinematic.
: :P

No? Cortana talked about how rampancy ends an AI's life, and she talked about her life and experiences in the past tense in the last cutscene. There's also "show, don't tell"-- you shouldn't have to have the characters state what's happening. We saw her fade away and the ship she was in fall to pieces, and there was nothing-- shown or told-- that contradicted that.

: To put it another way, watching two characters talking doesn't hold the same
: meta narrative weight as a detached narrator describing events to us
: concerning two characters and confirming for example, "And then
: Cortana was no more, never to be seen or heard from again."

Halo doesn't use an omniscient narrator, and that doesn't work with a lot of stories.