As far as that goes, what WAS the original bargain between DD and Petunia?
In the first book Harry is left on the Dursley's doorstep with nothing more than a letter -- and the Dursley's took him in. Why? They obviously didn't want him and could have easily hid the letter and called social services (or whatever they are called in England.)
Then there is the Howler that DD sent Petunia in OOTP. "Remember my last!" I definitely feel that Petunia is going to be figuring more in the next book... but in what way, I have no idea.
However you look at it, the last book will have to be at least twice as long as any other - with all the resolution to bring.
I never have figured out what Petunia is getting out of this whole arrangement. She despised her sister, so taking Harry in wasn't out of love or loyalty.
I keep thinking about one of the conversations DD had with Harry about the prophecy. DD seemed to be saying (and I was reading quickly, so forgive me half-formed thoughts)that the prophecy itself could be utter nonsense. Voldemort, by his own actions, created the circumstances which, supposedly, fulfilled the prophecy.
I almost got the impression that DD does not think Harry will, or needs to, kill Voldemort. DD was emphasizing Harry's goodness and capacity to love. If Malfoy, who is a putrid slug, couldn't kill DD for his Lord, can we expect that Harry (the good and pure) will be able to kill LV? The thought that Harry wouldn't kill LV is kinda ludicrous to me, but this conversation seemed significant to me.
Is there a way to make things right in the wizarding world without killing Voldemort?