The tweet from the author who found this secret: https://twitter.com/xepyal/status/1155837127487369216Apparently he stretched a QR code that appears in a split of a second in the trailer and it led to this audio.
As it sounds, Cortana finds that her fragments gone rampant and eventually became the evil space dictator from Halo 5. The Cortana who "died" in Halo 4 is still alive and she realizes what happened to her fragments.
C'mon, this is messed up. It destroys the entire purpose of this saga. So Cortana is not dead, the evil Cortana is not real, just a rampant indepentent fragment. All the destruction and death she caused is non consequential now and Chief can easily destroy the evil fragment with no emotional investment at all.
At the end the good Cortana can be restored to her original version and she can attach to Chief with no problem and they lived happily ever after.
Please, the game is not out yet and all of this is just speculation, but if we assume what the hidden audio suggests, everything that happened to the end of Halo 4 and Halo 5 is not what it looks like it is and it is probably one of the worst possible incomes this story can make. If we were expecting redemption from 343 after the bad story of Halo 5 we are probably getting something worse.
So it's just as I feared. Cortana as we know her did not die at all and the abomination from Halo 5 claiming to be her is just an evil clone.
How far Halo has fallen from the dramatic, engaging and entertaining storyteller it used to be, and I use that phrase lightly. I know Bungie wasn't the greatest ever storyteller themselves, but damn it all if Halo CE through to Reach's ratings don't speak for themselves.
As I see it, this is 343 admitting they yoinked up and are subsequently pressing the reset button. Chief's back to being a blank slate (all of his previous experiences having no effect on his character whatsoever), Cortana is neither dead nor evil, the Covenant will most likely return to being Public Enemy No.1 (exactly as they appeared first in Halo CE no less. No Brutes, no Engineers, no Drones, no Skirmishers. Just the Grunts, Jackals, Elites and Hunters), the events of Halo 4 are well and truly erased and now Halo 5 is being basically handwaved away like it happened but no great acknowledgement is being paid to it other than 343's selective important bits.
I'm definitely not getting the game now, but that's just me. I don't know what it means for the fandom as a whole, other than fans who wanted their nostalgic Halo back being satisfied. Honestly, I don't care much either.