Several theories here. Please note this is a scattershot attempt, some of these theories are inconsistent with each other.
#1) The importance of socks in the books
J. K. Rowling has been trying to subtly indicate all along that Voldemort (notice how creepy and inhuman he looks) is not a real human! He is Dumbledore’s sock puppet. At the end, Harry Potter will vanquish Voldemort, and right before Voldemort draws his last breath, the serpentine mask will slip off, revealing the face of the kindly Dumbledore. Why??? screams Harry?
This whole charade was a plot to train Harry Potter to be the next headmaster of Hogwarts - each headmaster must go through an excruciating initiation, and Harry has passed with flying colours. Head bent in sorrow, Harry slowly makes his way to Dumbledore’s office, where Hermione (Hogwart’s newest teacher of Arithmancy) and Ron (youngest ever Minister of Magic, with Percy as his assistant) come to congratulate him.
2) Dumbledore, not really dead.
On the third day after the funeral (the students having already returned home), McGonagall heads slowly towards Dumbledore’s tomb to reverentially law down a box of Fizzing Whizbees. But heavens! What’s that she sees? A side of the tomb seems strangely translucent?!? A tall figure emerges. Blinded by the sunlight, McGonagall whispers “Is that you, Hagrid, the gamekeeper?” Then the mysterious figure waves a wand, her eyesight clears, and she recognizes Dumbledore! Dumbledore asks her to gather the remaining eleven teachers of Hogwarts (Snape having left the school) and commands them to keep on teaching at the school, and to help spread Dumbledore’s teachings (love is the most important thing, but if someone hurts your family, hunt him down and kill him, etc.) Then Dumbledore is taken away by Fawkes and disappears in the sky over the astronomy tower.
3) Harry Potter, househusband
At Bill and Fleur’s wedding, when everyone stands to deliver their toasts, Ginny also stands, and makes a surprise announcement: she and Harry are expecting a little Potter! Harry is the first to faint, but is brutally awakened by Mrs. Weasly kicking his butt all the way from the Burrow to the local Wiccan chapel where they have a pagan wedding, after which Arthur Weasley gets him a low-paying entry-level job at the Ministry. With the mortgage payments and the diaper changes and all, Harry has no time for hunting down You-Know-Who, who, upon finding himself ignored by his major adversary, withers away and dies, his life having lost all meaning.
OK, let’s go on to something more serious.
Snape, without a doubt, killed Dumbledore because he and Dumbledore had an agreement, Dumbledore’s “please, Snape” means “please do what we agreed on”, Snape not a “good guy” per se but a quadruple agent. As I have said a couple of times before, Dumbledore trusted Snape because Snape made an unbreakable vow to protect Harry Potter; Snape was in love with Lily Potter and turned away from Voldemort when Voldemort told him “this prophecy you told me about, obviously it means that I have to kill Harry Potter, and while I’m at it, I might as well do his folks too.” As Dumbledore says (Half-Blood Prince, chapter 25) “You have no idea of the remorse Professor Snape felt when he realized how Lord Voldemort had interpreted the prophecy, Harry. I believe it to be the greatest regret of his life and the reason that he returned —” Why would Snape regret this so much? Because he loved Lily. Q.E.D.
The prophecy says that either Voldermort or Harry must die, but not that one must kill the other. To kill Voldemort would require an Avada Kedavra curse. It is pretty obvious that J.K. Rowling is writing from a non-american mindset (in an American tale, the good guy would be mowing down evil-doers left and right and happily have doughnuts for breakfast afterwards): murder is a very serious business and not accomplished lightly (see Draco the wimp unable to kill Dumbledore.) Harry Potter was unable to even perform an acceptable Cruciatus curse on Bellatrix Lestrange after she had just killed his godfather! Avada Kedavra would be much more difficult. In the final confrontation, Wormtail will intervene between Voldemort and Harry and get killed by Voldemort, thus paying his debt to Harry; Voldemort will be standing over Harry, wand ready to get him; then Snape, a known Death-Eater who obviously has the right mindset to perform a killing curse, will zap Voldie from behind, and Voldemort’s last word will be “You?” in disbelief, realizing that he, the master of legilimency, has met his match in the occlumens Severus Snape.
We will have much to learn from Harry Potter’s visit to Godric’s Hollow. If J. K. Rowling has kept him away from his parent’s house for so long, it must be for an important reason.
Dumbledore has not finished imparting his wisdom to Harry. Dumbledore’s old pensieve will have many interesting tidbits. As mentioned in this thread, Harry will also use the pensieve to see what happened the night his parents died.
Lupin will get Greyback the werewolf; Neville Longbottom will avenge his parents by the capture of Bellatrix Lestrange.
Fish, your comment relating the four founder’s relics to the Tarot suits was clever. The four suits are: swords (Gryffindor), cups (Hufflepuff), wands (hence the significance behind the disappearance of Ollivander! good catch, that, I never would have put that together), and the fourth can be coins, disks, or pentacles. I am guessing that Slytherin’s locket, that was (unknowingly) found by members of the Order of the Phoenix during the housecleaning in book five, is shaped like a disk or has a pentacle on it.
