There were a few retcons between the original books, Halo: Reach, and the content between 5 and Infinite, but compositing the best of all three into a series would be ace.
Multiple perspectives could be adapted from Red and Blue Teams at Castle Base, the Spartan 3's from Reach, et cetera. At the end, we see Noble 6's sacrifice and a fragment of Coratana being delivered to the Pillar of Autumn, Linda and Jon going into cryo, and Pillar finding Halo (the start of CE).
The golden age of Halo was pretty much the time of CE, 2, 3, ODST, and Reach (at a stretch -- It's pretty divisive). Halo 4 onwards has been a massive letdown, tbh.
I'm burned out on Reach.
Reach was a pretty good book. But then it was adapted into a video game, and that split the fanbase so hard, you still find the occasional old-timer bitching about it.
So we had a game and a book. But then there was a comic adaption of the Fall of Reach. A comic written by Brian Reed, who would go on to be pretty damn divisive himself.
Then came an animated adaptation, which was pretty lame. And then Ground Command, a pretty cool wargame that could have been set anywhere, but it was set on Reach, and then suddenly it didn't exist anymore.
If Halo is going to have any life breathed into it, it can't keep treading old ground, especially not ground that's been worn into a rut.
That's fine, there's like dozens of Spartans and shittons of UNSC Marines/Navy personnel you could showcase in a cool movie.
Pretty much this. I'd rather have something new, with new characters set in the Human-Covenant War. In fact, set it at the beginning of the Human-Covenant War. So much shit was unceremoniously dropped in the first episode, it was a travesty. You don't need to explain all of this stuff to the audience, but when your introduction of the Covenant is that they're something nobody really cares about, or when your introduction of the
High Prophet of Mercy is to have him call upon a girl at her apartment, you're fucking the dog.
Gimme a show that starts in the early war, with a squad of Marines-
Yeah, I'm not interested in a soft fix.
OK, you start with an LRRP squad of Marines rotating back from leave after Operation Trebuchet. Get them ready to fight Innies, and then the news drops.
We lost contact with Harvest.
There's confusion, uncertainty, some jokes about how the Innies must have been starving for corn, until the update hits.
Harvest isn't there anymore.
Aliens burned it to the bedrock.
What follows is stages of realization as it sinks in that aliens are out there, and they want us dead.
So these guys get mobilized and suit up to go to Harvest, where they're some of the first to fight the Covenant on the ground. Treat the Covenant as a mystery. Have them learn things that are gobsmackingly obvious to us, like the fact that the Elites are in charge and have energy shields, or weird stuff like the fact that the Jackals can see right through the UNSC's adaptive camouflage technology, and plain camo is better.
Eventually, as nuclear winter sets in and the UNSC and the Covenant get better at fighting each other, they start escorting scientists into the field to gather information.
But why no Spartans, you ask?
Simple. When the Spartans show up and the LRRP team finds itself working with the Spartans all the time, the fact that the Spartans are child soldiers is a surprise for the audience as well as the characters. This could give us what Halo really lacked for a long time: an outsider's view of the Spartans before they were famous.