AIs are only supposed to get 7 years. She knew death was coming sooner than most of her comrades since she was created. It was a bit cheap to even entertain the idea that she could cheat death by 'recompiling her neural net.'

No-one else get's a free pass. Both Keyes are dead. Truth & Mercy are dead. Johnson is dead. 343GS is dead. Gravemind is dead. Tartarus is dead. Bring any of those back

Then again, part of me wishes the both Chief and Cortana had stayed floating in space forever.