I'm just throwing it out there... Halo 2 sucked for campaign. It's been my worst Halo experience throughout the games, but more so because I never had H2 multiplayer until after H3 had been released. Reach sucks just as much as H2 did. I was disappointed with the removal of Assault Rifle, and the campaign to me was stale and boring. There wasn't as much excitement in it as there was for me in H:CE, or H3. Reach had a **** campaign though... so... maybe it's just hit and miss for me. Spoiler I think the chief and cortana have both been integrated with the domain. But, the only fault with your theory is; why would Cortana leave the chief if they were truly together? The digitised consciousness cannot be replicated with a lifeform, it can only be transferred. The original being is terminated in doing so... otherwise, why would Didact require thousands of human lives for his prometheans, if he could simply copy one soul into a thousand promethean knight forms? It's a typical move to have clues left behind as to what actually happens next... I've just had a massive hour and a half long discussion with dreaddraco2 about knowing a prehuman empire existed prior to the books and Halo 4 confirming it and it was down due to hints in game, media, legendary edition content etc... that hinted at these. For example, terminal information discussed pre-historic humans in a devolved state and the librarian saying they're special. They don't reference human's by nature, but it's the final gateway to the Ark (Which we know is on Earth), and she refers to her garden as Eden which is obviously linked with our bible. The other hints are the two separate classifications of Humans, known as 'Humans' and 'Reclaimers', both having similar statistics except the star position being Epsilon Eridani II for Reclaimers... Anyway, cutting a long story short... it's often you can figure out what's going to happen next in the games if you look at all the information you've given and start filling in the holes yourselves. Knowing what we know from the Spartan Ops videos, you can start to piece together some form of storyline what could come to fruitition in Halo 5 or even Halo 6.
at Atik Spoiler easy explanation for the final boss fight other than what you said about bungie hating halo 2 and not doing boss fights the right way, per the ending where the didact is talking about how its not over and humans are the mantels biggest threat etc, thats either A. unescessary back story that isn't needed and only the fans that read the books would get due to the war against forerunners eons ago or B. the didact didn't die, he somehow survived or got digitized by falling into the composer, which i assume just digitizes human's doesn't really kill them. The spartan ops episodeds is going way off key of what we thought the device is just a telportation system but that off topic. I beleive that the didact is alive and will return with either A. a ton of promethian or warrior servant knights and a fleet or he himself will be an AI of some kind.
Spoiler I suppose the ending is open to interpretation. The composer is only designed to absorb 'Human' life forms though. The reason the chief is not affected by this is because he is actually a 'Reclaimer' lifeform. The Legendary Edition of Halo 3 has the two classifications of mankind in the 'Bestiarum'. A 'Reclaimer' life form can either be human, or forerunner by genetics and it is a lifeform that possesses the ability to activate Forerunner technology... or so I've read about it anyway. So, if the Didact fell into the composer - he wouldn't be digitised because the composer would reject his genetics. There is apparently a second Didact still alive (as there were two forms of the Didact in the books, although I thought the original Didact had been killed by the Master Builder) which Halo 5 and 6 could both be about. As for the final cutscene, I think those parts were added in so the games were more like Call of Duty sadly. I hate them personally, I feel a lot more submersed into the game when the cutscenes are playing because the way the chief reacts to things is a genuine reaction (as opposed to a player interaction). While it doesn't feel like YOU are saving the world, you can witness the struggle the chief is going through to save the world which is just as powerful.
Spoiler yeah didn't think of that although early books made it seem that human beings themselves were reclaimers all of us idk. I agree that the 2nd didact may come into play although if its Bornstellar he won't be evil, i don't even think the real didact is evil, this may have been a play on the book where bornstellar released the didact who was imprisoned?? I had another thought on the whole cortana cheif thing, i doubt 343 will kill John off, would be too off putting, Cortana may not ever come back but here is a thought ........ what if we fill Cortana's position with the surviving members of John's squad? Kelly is like his true love that he thought he lost long ago boom there ya go sub for Cortana, could also make for a really cliche love story but also show John is human too.
Spoiler Ok, so I was thinking about the last bit, which (sort of) hints that the Didact didn't die, and that before Chief gets found, Cortana says that most of her is "Down there" referring to the Didact? So if the Didact is still alive and Cortana is with him, then we know what we'll be doing in H5...
Joined so I could add my potentially irrelevant 2 cents and because i'm just a big lorewhore ^^ Spoiler I was under the impression that what the Didact fell into was a slip space portal and not the Composer's beam/energy. Also the Ur-Didact is still alive and appears in the next Forerunner book, as he was apparently abandoned by the Master Builder on a Flood infested planet rather than executed. Of course that doesn't rule out him dying in the new book mind you.
Below is the book description for Halo: Silentium. This ought to keep us thinking for a while (at least until March)... "In the last years of the Forerunner empire, chaos rules. The Flood—a horrifying shape-changing parasite—has arrived in force, aided by unexpected allies. Internal strife within the ecumene has desperately weakened Forerunner defenses. Too little, too late, the legal rate of Juridicals is only now investigating possible crimes by the Master Builder and others. Evidence-gathering agents known collectively as Catalog have been dispatched to collect testimony from the Librarian and both Didacts: the Ur-Didact, treacherously abandoned in a Flood-infested system, and the Bornstellar Didact, who accompanies the Librarian as she preserves specimens against the dire possibility of Halo extermination. Facing the imminent collapse of their civilization, the Librarian and the Ur-Didact reveal what they know about the relationship between the long-vanished Precursors and the Flood. The Precursors created many technological species, including humanity and the Forerunners. But the roots of the Flood may be found in an act of enormous barbarity, carried out beyond our galaxy ten million years before... Because of that barbarism, a greater evil looms. Only the Ur-Didact and the Librarian--husband and wife pushed into desperate conflict--hold the keys to a solution. Facing the consequences of a mythic tragedy, one of them must now commit the greatest atrocity of all time—to prevent an insane evil from dominating the entire universe."