Your already removing the Halo installation (which i understand, time for something more… fascinating and spectacular!) BUT Still, still, Cortana and the master chief are the 2 staples of the Halo Franchise! DO NOT kill her off!
Suggestion and Advice:
Find away through Forerunner Tech to prevent her rampancy all together! i mean… FR AI’s last up to 100 000 years or more!
DO NOT kill Cortana! or make her an Enemy… for long at least! Let the chief talk her down or something…
Maybe a Obi-Wan Kenobi thing can happen. He dies but lives on through the Force. Cortana dies but lives on through whatever Forerunner mystical thing there is.
343 Industries killed Halo. Not only Cortana but all of Halo. It wont be the same without her. And what is the Master Chief new job since she’s “gone”? I bet Bungie wouldnt have killed her off.