All of the information below was gained by different web-sites and are either rumors or facts that have been approved by J.K herself.
The last chapter was written in 1999,rumored,and the last word should be 'scar'. However, the fact about the last chapter could change as Rowling gets deeper into her writing.
It will contain a lot of background on the Potters.
The Sorting Hat is not a Horcrux.
No book character has returned fron the future.
There is significance to the fact that Harry has his mother's eyes.
We will find out something very important about Harry's mother.
We will find out who R.A.B is
Krum will return to the scene
Umbridge will reappear
Harry will visit Godric's Hollow
There will be no more Quidditch