Do you think this will be part of the main plot in Harry Potter and the Deathly Hallows?

no there isn't a secret. I think i read somewhere on a review that James potter was pure blood Harrys mother was mudblood but was chosen to go to Hogwarts. even so from what was concluded about the 6th book he just has to find the horcruxes, and weather or not he finds them will be the final installment. ok Voldemort couldn't kill harry when he was a baby because when harrys mother stepped in front of voldemort and died for him it gave him the ultimate protection which was love. Voldemort couldn't kill him because his mothers love protected him but now voldemort can because of something that happened in the end of the 4th book. the 7th book will determine weather or not harry potter or voldemort dies it has to be one of them, and because of a profecy, Harry Potter is the only one that can kill voldemort but now that voldemort has his blood it's hard to determine which one will live and which one will die. and the profecy is now filled because voldemort chose harry even though it was suppose to be harry or neville. Since voldemort chose Harry That's the profecy and once again the profecy stated that Harry is the only one that can kill voldemort so once again we arrive at the statement that either harry or voldemort will die in the next book.