First things first, this isnt a blog supporting or not supporting Annabeth as the last of the Seven, there are enough of those right now. This is more of a blog detailing Percy's conversation with Hera at the end of The Son of Neptune.
First off, I'd like to note that Hera has been shown in the series so far trying to get the seven together. She was Leo's babysitter, she appeared to Frank before his stick burned, she switched Percy and Jason to unite the camps, she told Piper to save her when she was captured, but Hazel died possibly before she could reach her. This means that at least she is working toward forming the group. After Hera appears to Percy at the end of the book and they start talking about Annabeth that bringing the seven together becomes confusing.
Hera says that the person closest to Percy (and the one who hates her the most) will cause him the most trouble "when you arrive in Rome." I highlight the "you" above because Hera could be using it in the singular or plural form. She could mean Annabeth has a hard task when Percy (and the other confirmed 7) leave for Rome or a hard choice when Percy and Annabeth (and the other confirmed 7) go to Rome. Either way, she has a hard task.
When Percy tries to counter saying that Annabeth is the person he most wants watching his back, Hera makes a "we will see" comment. Now I know that gods can never answer a question directly as shown several times in both series, but this conversation seems especially vague to me. If Hera is trying to bring the 7 together, why is she talking about Annabeth as if she will rip the 7 apart? I dont know if Annabeth is a member of the seven, but this conversation is one of the weirdest bits of dialogue I think in the series. I hope the next book comes out soon because this conversation is going to drive me crazy.