I haven't read all the replies yet, but this is really cool!
The Trio--lives
Voldemort--dies
Snape--is innocent! Well, on the side of good, at least. DD was dying from his withered hand and cooked up a plot to put Snape beyond suspicion so he could help Harry kill Nagini and Voldemort. Snape will die heroically in a way that leaves no doubt as to his true intentions. I'm not sure why DD trusted Snape, but I've always believed he was in love with Lily somehow and became full of regrets when he discovered he caused Vold. to kill her.
Hogwarts--I think it will be closed, but it could go either way. It might be open with only a few students. However it goes, the trio will need to go there for info and guidance.
Horcruxes--apart from the locket found at Grimmauld place, I'm not sure yet. I haven't hit HBP in my rereading. I'll come back and edit next week. I don't think Harry is one.
Other deaths--Percy (under Imperious and finally shaking it off), Wormtail (saving Lupin from Greyback with his silver hand), Bellatrix (killed by Neville), and Hagrid. I'm not sure, but I had heard that Alan Rickman and Robbie Coltrane were the only two actors JK told the final fates of their characters to, which would indicate to me that they both will have screentime and good death scenes and she was trying to keep them from leaving the series by telling them about it. There will probably be other order members and death eaters dying, but nobody we've come to care for too much.
Other predictions: Sirius, DD, James, and Lily will help from beyond the grave using Sirius' mirror.
One or more of the trio will time travel and be under the invisibility cloak on either the night of Harry's parents' deaths or a day or two before. They may have had to travel back to get a Horcrux and may actually meet James and Lily, warning James to leave the cloak with DD before he dies.
Harry will return to Hogwarts as the DADA teacher either immediately or following a pro-Quidditch career.
Somebody will use the Draught of Living Death mentioned in Snape's first lesson in book one.
Generally, I think she'll set up the book so that the trio has to ask for help from our favorite characters for each Horcrux. So maybe the Weasley twins help with one, Lupin and Tonks with another, etc. They don't need to tell them what they're looking for, but the three aren't trained enough yet to do it all alone. This will let us see our favorites in action one last time.
Follow Mothering