As has been brought to my attention by a reader, my earlier speculation that Dumbledore would not die in this book was incorrect. However, the essence of that post was on the significance of Snape:

Snape commands, for reasons as yet unknown, an uncharacteristic degree of trust and respect from Dumbledore - uncharacteristic with respect both to how Snape is treated by most people and the trust Dumbledore has in most people. The books are nothing if not suspenseful and twisting (albeit everything always makes sense in the end, unlike plot twists in so many contemporary novels), so I expect this one to be no different.

Snape is clearly a lot more important than we have given him credit for, and has put himself at substantial risk with the Death Eaters in Phoenix. I think a possible scenario would be that just after learning why Dumbledore trusts Snape so much, and, in turn, how important Snape is to the Order, Snape is killed. We may even like him by that point.

Even Professor McGonagall mentioned that Dumbledore always implied that he had a rock-solid reason for trusting Snape. And Dumbledore, even moments before being cornered by Malfoy, was seeking out Snape in his time of need. And, certainly, his pleadings of “Severus, please…” are open to most any interpretation. Was he begging Snape not to kill him? I would wager not; I’d say that he was insisting that Snape do something that he did not want to do, but had told Dumbledore he would. Dumbledore seemed to think that he might be dying soon; remember that he made Harry promise explicitly that, if told to, he would leave Dumbledore to save himself. Likely, Dumbledore had similarly intimate discussions with Snape, the man he trusted so much.

Now, instead of us getting to like Snape (at least a little more) this book, we are certainly given every reason to dislike him even more. Yet there is still strong evidence that Dumbledore was right in trusting Snape. Although we didn’t realize it, and he seemed to not believe Harry, in truth he not only believed what Harry said he thought Malfoy was doing, but, according to what Dumbledore told Malfoy, knew what Malfoy was up to. But how could he be certain? Well, if Snape were telling him what Malfoy was doing! But wait – wouldn’t that also mean Dumbledore would know the purpose of Malfoy’s actions, i.e., that Malfoy was supposed to kill Dumbledore?! But of course!

If Snape were loyal to Voldemort, then he would have covered up what Malfoy were doing. But, presumably, he was Dumbledore’s source of information. Dumbledore would have also known about Snape’s unbreakable vow. It would make perfect sense that Dumbledore and Snape would have discussed how to proceed under the circumstances, planning for various potential exigencies. Perhaps Snape has, either now or much earlier, made an unbreakable vow to protect Harry as well. Snape’s relationship to Harry’s parents may be more than it seems, too. Think about this (from Letters of Marque):

Well, cast your mind back about twenty years, when Harry's mom and dad were at Hogwarts. In particular, think of the memory that Harry found in Snape's Pensieve. What happened? Snape was picked on by James Potter, Harry's dad, and Lily stood up for him. Remember, this is Snape's memory — James, in that memory, is a swaggering bully. Pay particular attention to Snape's memory of Lily Evans (later, Lily Potter). It seems totally obvious — Snape has the biggest crush on her. Note that Snape's impression of her — as a beautiful avenging angel, although he never specifically calls her that — is at odds with his actual words. He actually calls her a Mudblood.

My theory: Snape was driven (in part, by James' Potter's bullying; in part by his own somewhat suspect inclinations) to be a Death Eater. Once he found out about the plot to kill James & Lily, though, he turned to the good side and told Dumbledore what was going on. (This is why Dumbledore trusts him.) Unfortunately, he was too late to save Lily. He hates Harry 90% of the time because he looks like James, and 10% of the time because he can't stand to look in Lily's eyes, knowing that if only he had tried harder, she might be alive.

Now, according to search engine queries that are bringing people to JNOV lately, a lot of people are concerned about Dumbledore’s death. In fact, a lot of people seem to be asking if Dumbledore is actually dead or not. Is Dumbledore really dead? Did Dumbledore have to die? Why? Of course he is dead. The story has an intricate and surprising plot, but it’s not a soap opera. Maybe Snape’s Avada Kedavra curse was insincere or otherwise incompletely executed, but, even so, the fall killed him. And why would Fawkes have left if Dumbledore weren’t gone forever? Did he have to die and, if so, why? That's harder. Hmmm.