I can see there being a replacement Cortana that might come at odds with Chief and he might reject it in favor for his memories of Cortana in the past trilogy, but I think that's what people might be missing. imo, Cortana is [b]dead[/b]. She's not coming back. She is, pure and simply, dead and... deleted... whatever happens to computer programs and other artificial lifeforms. To spoil Mass Effect 3 here quickly [b]AND YES, I AM SPOILING A MASS EFFECT 3 THING HERE[/b], she's going to be something more along the lines of Legion, imo, where she's dead but the [i]memory[/i] of her lives on. While she's not exactly like our Geth buddy Legion in that her death brought about the sentience of the Geth, I feel that her death will be referenced and used as a focal point to develop John over the course of the new trilogy. He'll probably be haunted by her final words and have to cope with the death of, literally, his best friend since Blue Team for the entirety of the Human-Covenant War's end. As we could plainly see at 4's end, John was simply hiding his grief from Lasky with his usual wall of stoicism; I think he's broken inside, moreso than usual. imo, 343i would be shooting themselves in the foot if they killed off Cortana only to bring her back in 5 or 6 in any way, shape, or form. If anything, I see Chief's development being something similar to Church's from the popular Halo webseries [i]Red vs. Blue[/i], where the entire point of 5 and 6, along with fighting Storm Covies and whatever else the UNSC feels the need to throw their biggest asset at, is getting OVER her death. To reconcile and move on with his life. [i]"No, Tex, no. I'm not going to say I love you. I'm going to say I forget you. I forget you. ... I'm letting go." - Epsilon Church (Red vs. Blue Season 9 Finale)[/i]