With all the speculation about book 7, I want to put my predictions on the record, so I can go 'IN YOUR FACE!' if they're true, or hide in a closet if they're not. So!
Fred Weasley is going to die. We all know one or more of the Weasley clan is going to die. There is constant evidence supporting it. The entire Weasley family, 9 in total, are a huge part of the series, and all, except for Percy, are involved with the Order of the Phoenix. They are, essentially, the perfect family. It would be very unlikely for all of the nine to make it out alive. I believe there is substantial evidence, along with a lot of guessing, that Fred will die. We've seen already that their new line of Defense products at WWW can be useful to the good and bad side, as evidenced by Malfoy when he uses the Peruvian Instant Darkness Powder. I have a feeling it won't be long until the rest of the Death Eaters discover these useful products. I believe they will attack Fred and George's store - most likely in the middle of the night - and the twins will have to fight them off. Fred, being the more dominant twin, will die fighting to save George.
Snape is/was in love with Lily Potter. Most of my speculation about this theory comes from the fifth book; not just from the Pensieve scene, but from Harry's Occlumency lessons. Snape is, shall we put it, very apathetic and indifferent to everything. I can't remember the exact quote, but at one point when Harry says he's having a hard time closing his mind, Snape fires back saying that those who wallow in their misery, and those who wear their hearts on their sleeves - weak people, will never stand a chance against Voldemort. There is too much detail in that quote for him to be simply objectional. From this quote, one can derive that he is afraid of his emotions. And from what we know about Snape, which is very little, we can deduce that James and his friends did not have that large an impact on him for him to turn out completely rotten. There must be another factor.
In the Pensieve scene, Snape is being tortured and mocked by Sirius and co. Lily comes to his aid by shouting, 'LEAVE HIM ALONE!' Snape, who seems ashamed or embarrassed by Lily, calls her a mudblood, and Lily is shocked, but recovers quickly and calls him Snivellus. I don't think this is Snape's worst memory because of what Sirius did, but because of what Lily did. Lily, even though she was helping him, was also using him as something of a toy in her budding relationship with James. It was obvious to Snape that there was something going on between them, and indeed something to yet happen between them.
Also, just on a small note, over the years Snape has tormented Harry, constantly bringing up his father in a bad light. Snape has never, to my memory, bashed Lily. Why hasn't he? She was a mudblood, making Harry a half-blood, and she was everything Snape was not. Pretty, popular, nice. Even though James was a git to Snape and deserved some of the bashing he received after his death, it seems strange that never has Snape brought up Lily. (For more convincing evidence, go here.)
Neville Longbottom is going to die. Throughout the series, Neville has developed incredibly, from a nervous, klutzy, and forgetful boy to a strong, brave young man who wants to avenge his parents. And add the prophecy into that mix, and you've got a very important character to the 7th novel. I believe Neville will avenge his parents by killing Bellatrix, but he won't live to see the end of the novel. I think it's mostly because, even if he does kill Bellatrix, there's no hope for a happy ending for him. His life is such a tragedy, and it's difficult to imagine him moving on, with or without Luna or whoever at his side. He, unlike Harry, does not have strong, loyal friends. Sure, he is friends with the trio, but they are in no way as close with Neville as they are with each other. Ron, Hermione, and Ginny are Harry's reason to live. So far, it seems, avenging his parents is Neville's sole reason for enduring the hardships in his life. The 'right' thing would be for Rowling to have Neville die heroically, satisfied that he has avenged his parents, and in some way his death will help Harry overcome Voldemort.
Ginny, Harry, Hermione, and Ron are all safe. All these rumors that Ron or Hermione are going to snuff it don't fool me. Ron and Hermione parallel Harry and Ginny. In a previous post, someone gave very good evidence based on other epics, that Harry and Ginny need each other to survive. Why else would Harry break up with Ginny, if not to get her back after Voldemort is finished? And in this novel, we all know Hermione and Ron are going to get together. I don't care how long this novel is, you can't have Hermione and Ron get together, and then one of them die. It's too much for one novel. Same with Harry and Ginny. There's not enough time for them to get back together, and for one of them to die. If Harry is going to live, which I fully believe, and if he's going to have his happy ending, he will need Ron, Hermione and Ginny at his side.
Peter Pettigrew will redeem himself. This one I'm not sure about, but I have enough evidence for it to seem possible in my eyes. Pettigrew is a coward who turned to the dark side because he believed it would keep him safe. There has never been any other reason stated in the books that he might join the Death Eaters. It would appear that he has no ill wishes towards Muggles or Muggle-borns. After all, one of his best friends married a Muggle-born. As small a problem as this may be, I don't think Rowling will leave it a loose end. Pettigrew is a good person, I believe, who just let his cowardice get the best of him. He is certainly not evil. And, he also owes Harry a life-debt, which I believe Harry will be calling on him for. If he lives or dies is not as big a deal to me as long as he redeems himself.
. . . .
So those are some of my big theories. I have some questions as well, that I hope Rowling will answer in the 7th book. Feel free to give your opinions on them!
How did Harry inherit so much money in his Gringotts account?
How is it that none of James's relatives survived? Where did they all go?
Which is the Dursley's displays some form of magical power? (Personally, I think there is a lot we don't know about Petunia. Maybe she won't be magical, but I believe she's very important to the novel.)
How did Petunia hear 'that awful boy' telling Lily about dementors so many years ago? Lily and James didn't get together until their 7th year. Petunia was also not at their wedding, and James and Lily died only years after that. Also, we know that Petunia had lost contact with Lily for many years. There is a timelap here that Rowling might have missed purposefully. And is 'that awful boy' really referring to James?