I hope Atriox survives Halo Wars 2 because The Banished might be the most compelling piece of post-war lore that the franchise has. Atriox certainly seems as though he has the ability to coerce the remnants of Jul 'Mdama's Covenant into joining the Banished given that they would both be politically opposed to 'Vadam controlled Sangelios.
Also, as of late there's been a terrible habit of killing off the main antagonistic forces of the franchise without any payoff. Just for comparison:
Sesa 'Refumee: Two mission miniature saga devoted to chasing him down, ending with a personal fight with him.
Prophet of Regret: He assaults Earth, you take a mission to repel borders in orbit, two missions to defend New Mombassa, two missions to chase him across Delta Halo ultimately ending with you punching him in the fucking face.
Tartarus: Spend two levels chasing him to Delta Halo's control room and then kill him yourself in order to prevent him from activating Delta Halo and killing all life that exists.
Brute Chieftan in Sierra 117: Chief gets constantly harassed all level by a single Brute Chieftan, whom you find out has captured your B team, giving you a personal stake in his death. You kill him yourself.
Prophet of Truth: You literally chase this fucker over the entire game through New Mombassa to the Ark. You fight climactic battles to prevent him from reaching the cartographer and the control room, but ultimately fail. You have the largest battle in the franchise so that you can kick his door down and take the elevator to the top floor penthouse that he plans on ending the universe from. You fight alongside the flood to clear a series of long hallways until you find Truth, and the Arbiter kills him with his own hands, giving a satisfying ending to his narrative arc.
Gravemind: After meeting this asshole three years ago, you're finally given an opportunity to do what you wish you could have done then and fuck his house up. You kick his door in, save your bestie that he kidnapped that you've been missing all game, and drag your ass up all thirty thousand floors of the pyramid to the control room, shooting a billion fucking dudes, where you set off the biggest bomb in the universe by killing the most annoying asshole in the entire franchise right after he kills your other bestie (RIP Johnson). Then you get in your car with your alien bestie (or four ghosts or whatever) and get the fuck out of there in the most tense race against time in the franchise.
The Didact: Your great-great grandpa that has force powers and hates all of humanity for some vague reason that your great-great grandma tried to explain to you through several short films or whatever. He's a bad dude, or so you're told. You chase him down over the course of several missions in a pretty epic chase, but you push him off of a bridge, killing your best friend in the process (RIP). Secretly, he lived, and your other best friends help you kill him later when no one (and I mean NO ONE) is watching. It's poorly drawn, and you and your friends don't like to talk about it.
Gek 'Lhar: Some nerd you don't know finds him and kills him in a movie you don't have anything to do with. He's a bad dude, or so you're told, but he gets bodied by a couple of scrubs.
Parg Vol: An easter egg about a game nobody played. He's a bad dude, or so you're told. You and your anonymous internet friends kill him because he exists. No one gets anything out of it because you're not tied to him in any narrative fashion.
Jul 'Mdama: The antagonist of Spartan-Ops. He's a bad dude, or so you're told. He's killed by Fireteam Osiris, who notably has nothing to do with him, unlike Fireteam Majestic or Fireteam Crimson (this probably was way more satisfying when Buck was Thorne). You fight your way through a room of unrelated enemies to get to the location of Catherine Halsey, but casually run into 'Mdama and effortlessly dance all over him and his squad. He's killed in a cutscene for a mission that he wasn't the objective of by a group that has nothing to do with him, ending the war once and for all.
The Warden Eternal (A): Cortana's beta orbiter. He's a bad dude, or so you're told. Defends his lady's chivalry while looking spooky and making silly noises. You fight him as Fireteam Osiris and have no idea what he is or why he exists.
The Warden Eternal (B): Cortana's beta orbiter. He's a bad dude, or so you're told. Defends his lady's chivalry while looking spooky and making silly noises. You fight him as Blue Team and think he's being a creep towards Cortana.
The Warden Eternal (C): Cortana's beta orbiter. He's a bad dude, or so you're told. Defends his lady's chivalry while looking spooky and making silly noises. You fight him on Sanghelios as Fireteam Osiris and wonder how he's there, and why the Didact didn't use the same technology to get his ship to Earth faster.
The Warden Eternal (D): Cortana's beta orbiter. He's a bad dude, or so you're told. Defends his lady's chivalry while looking spooky and making silly noises. You fight him on Genisis as Fireteam Osiris in a tank and are really fucking bored of the fact that he exists and seemingly has no narrative agency of his own.
The Warden Eternal (E): Cortana's beta orbiter. He's a bad dude, or so you're told. Defends his lady's chivalry while looking spooky and making silly noises. You fight him on Genisis as Fireteam Osiris at the same time as The Warden Eternal (F).
The Warden Eternal (F): Cortana's beta orbiter. He's a bad dude, or so you're told. Defends his lady's chivalry while looking spooky and making silly noises.You fight him on Genisis as Fireteam Osiris at the same time as The Warden Eternal (E).
The Warden Eternal (G): Cortana's beta orbiter. He's a bad dude, or so you're told. Defends his lady's chivalry while looking spooky and making silly noises. You fight him on Genisis as Blue Team so you can get to Cortana. You fight him alongside The Warden Eternal (H) and The Warden Eternal (I). After this he vanishes for no adequately explained reason. Probably because everyone is so fucking done with him by now.
The Warden Eternal (H): Cortana's beta orbiter. He's a bad dude, or so you're told. Defends his lady's chivalry while looking spooky and making silly noises. You fight him on Genisis as Blue Team so you can get to Cortana. You fight him alongside The Warden Eternal (G) and The Warden Eternal (I). After this he vanishes for no adequately explained reason. Probably because everyone is so fucking done with him by now.
The Warden Eternal (I): Cortana's beta orbiter. He's a bad dude, or so you're told. Defends his lady's chivalry while looking spooky and making silly noises. You fight him on Genisis as Blue Team so you can get to Cortana. You fight him alongside The Warden Eternal (G) and The Warden Eternal (H). After this he vanishes for no adequately explained reason. Probably because everyone is so fucking done with him by now.