In some of the descriptions for armor and weapons in the warzone footage it says didact "went missing" so he may not be dead. I will throw my Xbox down an elevator shaft if he's back.
Wait, they killed him off in a book? lol
I should have worded that a little differently
he got composed presumably in issue 10 of Escalation. You can Google that and you'll easily be able to find what I'm talking about.
I sincerely doubt they will kill him, especially in Halo 5. I don't believe that 343i would go out and advertise a significant plot twist like that and then have it actually happen.
The rest of Blue team is definitely on the chopping block though.
Simply because the game is playable entirely on 4 player coop, I can't see them killing anyone from Blue Team or Fireteam Osiris. It would be a really strange thing to try and shift the character someone has been playing as to someone entirely new to maintain the 4 person groups.