Locke's objective further clarified/Story concerns

With the new trailer building the premise that Master Chief is dead, I believe that Locke’s objective is to make it so for ONI. Rather than risk humanity’s now famous hero being shed in a less favorable light, ONI wants him dead so that they can write his legacy, as opposed to Chief forging his own.
Now, I understand they announced his death in 2560 and the first mission featuring Fireteam Osiris is in 2558. However, Blue Team’s mission comes afterward, and Chief and blue team are still under UNSC orders. This tells me that Locke may not even be hunting Chief until maybe halfway through the game.

Even if my theory is incorrect, the story of Halo 5 is simply soaked in complexity. I love it. I do fear that non lore nerds will have no idea what is going on, or what the context of the missions are. I haven’t played the game but I feel like I’ve known Blue Team for years after reading the books. I just hope that people who haven’t read the books or listened to #HuntTheTruth or watched Nightfall are offered an experience on the same level as me, because they will be the majority.
It’s imperative that players come to feel at home with Blue Team, and that their existence is given an in-game backstory and explanation. After reading some campaign impressions online from various sites, it seems many have retorted “Are they just making up more Spartans? I thought Chief was supposed to be the last one” in reference to Blue Team.
Please 343, give these iconic characters the justice on screen they were only previously afforded on pages.

The 2560 date was a mistake on the announcer’s part, ONI has fixed it and stripped the reporter of all of her duties.

It seems very likely that Chief was declared KIA to cover up him going AWOL, allowing Locke to hunt him down without many questions being asked. Blue Team goes AWOL immediately after the mission Blue Team, when they go to Meridian against orders.