So who will die as per the last line of the Great Prophecy of 7 ?
It most certainly is CHIRON !
^Now here goes my reasoning :
1) He said in TLH that he wants to peacefully retire. Which means he is no longer needed and so not Immortal anymore..
2) Then if he has taken an Oath on all sacred things that not to have the 2 camps united or talk about them or something.. And now it has been broken..'An Oath to keep with the Final Breath..'
3) If Chiron is captured then the 7 have to decide whether to save him or save the quest and Gods/ entire world.
4) Annabeth is way too close to Chiron to let him die.. She will go after him whether the others want or not.. 'Daughter of Wisdom walks alone.'
5) This will be another big sacrifice Percy will have to make - let Annabeth go alone which he cannot make but Frank will have to convince Percy to let her go.
'"Every hero has a fatal flaw. Percy Jackson?, he's too loyal to his friends. He can't give them up, not for anything. He was told that years someday soon, he's going to face a sacrifice he can't make. Without you Frank, without your sense of duty... he's going to fail. The whole world will go sideways & Gaea will destroy our world."
- Mars/Ares to Frank ; The Son of Neptune'
6) Annabeth will thus cause most problems in ROME as predicted by Juno..She will fight with Percy and all others and finally get angry with all of them and go alone to save Chiron..As much as she loves Percy, Chiron is like her father and she will do everything she can to help him. Percy can't give them (Annabeth and Chiron) up, not for anything. The whole world will go sideways that is because he'll have to go to a diff path to save Chiron and diff path to defeat Giants and Gaea- Just like in TLH - Piper's dad or Hera..! Remember Janus told him in TBoL your choice will come soon..
7) Thus Annabeth will have a tough path ahead whether she is up to it or not will have to be seen..