another year and a half?

so i've finished reading Harry Potter and the Half-Blood Prince, which was a really good book I have to say. unfortunately, i'm feeling some withdrawal symptoms now after the exciting climax towards the end of the book, and am rather anxious to see what happens in the final book. we all know it'll be a long time before Rowling publishes the final book, so in the meantime i'll have to learn to pick myself back up. anybody have any guesses who R.A.B. is?