What if Chief and Cortana died on August 29th?

Hello all, so I’ve been playing around with a what-if scenario these last few days and I’ve been pretty excited about it. It’s basically a fanfic idea where Chief and Cortana are both killed/destroyed during their initial test run as a pair. Ackerson rigs the test run, and the SkyHawk successfully kills Chief and destroys Cortana’s chip.

To get to this point the first thing I changed is that Halsey’s attempt to split Cortana fails, and possibly causes some damage to Cortana, perhaps in a way Halsey cannot detect. Halsey commits Cortana to remain part of RED FLAG and assigns Kalmiya to recover the data from the Babd Catha Forerunner vessel. Skip to August 29th where Chief and Cortana meet, however, there is no luck here, only doom.

How would the rest of the Halo story change? I imagine it’s a lot bleaker. Here’s what I’ve come up with so far, trying to fit all the lore pieces together to make sense as much as possible:

-Halsey physically lashes out at Ackerson who is in the room with her. He has his men detain her and claims she is having a breakdown over the failure of her Spartan and AI pairing.
-Halsey recovers somewhat from her shock and rage at seeing two of her greatest works obliterated by a missile, and with the help of Jerrod, sends a coded message to Kalmiya. She tells her what happened and instructs her to draw a recovery team to secure Kalmiya, preferably Spartans.
-Kalmiya, using intrusion software Cortana had, accesses records of NOBLE Team, and redirects them to SWORD Base.
-Jerrod is detected by Ackerson’s men or something and is deactivated, and Ackerson either leaves Halsey in a cell or takes her with him. I don’t know what he would do.
-NOBLE Team arrives at SWORD Base to destroy it, but are redirected underground and meet Kalmiya. They fight off Covenant forces while Kalmiya finishes decrypting as much data as she can, but time runs short. Noble Team is pushed back and Kalmiya lets them in and gives instructions on how to transfer her into a data chip.
-Noble Team escapes SWORD Base as it is destroyed and heads for the Asźod shipbreaking yards. Carter is wounded while en route, and Emile, Jun, and Noble Six drop out of the Pelican.
-Carter still sacrifices himself. Later, Emile is still killed by the Elite Zealots, but Jun takes the Onager and destroys the Battlecruiser while Noble Six escapes aboard the Autumn.
-Meanwhile, after Chief’s death Fred-104 is made team leader of the SPARTAN-IIs. Fred takes Linda-058 and James-005 to Gamma Station. James is still killed and Linda is gravely wounded. The Pillar of Autumn recovers Fred, Linda, and the survivors of Gamma Station and flees Reach.
-Kalmiya, not having access to the Sigma Octanus IV, or the same level of processing Cortana had, does not have the same coordinate information and is unable to guide the Pillar of Autumn to Installation 04. Instead, the Autumn makes a different slipspace jump to an unknown location. The Fleet of Particular Justice still follows.
-As for the Pillar of Autumn anything really could happen. I imagine they arrive at some Forerunner world, but the Covenant have no qualms about attacking the ship. The Autumn is destroyed while entering the atmosphere, and there are a lot fewer initial survivors.
*-*The human survivors dig in against the Covenant forces, and the Covenant do not glass the planet because of the abundance of Forerunner tech and structures. The humans eventually meet a Monitor and they eventually learn about Halo. The Monitor gives the humans a Builder ship to take them to Halo. I also imagine a cool fight scene between Fred and either Rtas 'Vadumee or Bero 'Kusovai at the end
-The humans escape aboard the Builder ship, but the Covenant capture the Monitor, and Thel talks to it to learn its secrets.
-Truth’s secret fleet stationed at Unyielding Hierophant invade the Sol system around the end of September/ beginning of October. The Home Fleet really has no chance against over 500 Covenant ships and is easily wiped out. Earth is invaded by an overwhelming Covenant force led by Jiralhanae. They would also start excavating the Portal at Voi.
-The Prophet of Regret still arrives at Earth on October 20th. When he arrives he finds a massive Covenant force occupying the Sol system, and he would be surprised and angry at this secrecy. I think the Covenant forces there would also be surprised a High Prophet just showed up, but would also obey him. Regret would be able to probably learn that Truth sent the fleet to Earth. Regret would be outraged at Truth for secretly amassing this fleet and attacking humanity’s homeworld, and also finding the Portal to the Ark. Now Truth would also be outraged that Regret had discovered the Portal and was going to find it without telling the other Hierarchs, and would be accelerating his plans to eliminate Regret.
-Truth secretly orders some Jiralhanae to kill Regret but his Honor Guards save him. The Solemn Penance flees into slipspace and travels to Installation 05. Brute ships pursue Regret.
-The Great Schism would begin with Truth denouncing Regret and the Sangheili. Fighting would break out across the Covenant Empire. Regret would attempt to rally Sangheili to Delta Halo.
-The Flood would probably still escape from Delta Halo and spread through the Covenant fleet.
-At some point the Autumn survivors arrive at Installation 04 where they are contacted by 343 Guilty Spark. He brings them to the ring and they learn the purpose of Halo and some of the history of the Forerunners and the Flood. The survivors consider holding the ring ransom to force a ceasefire with the Covenant, as RED FLAG was meant to do.

These are pretty much the things I had come up with so far. What does everyone think would happen? Feel free to point out lore pieces I missed or if you think something different would happen, and what you think would happen next. If something like this has already been posted I apologize for the redundancy.