First of all, I would like to thank Timon for singing this line in the Lion King. It works quite well for the purpose of this theory!For the entire series so far, Harry, Ron, and Hermione have been best friends- the Trio. With the Wizarding world at war, it is almost laughable to think that JKR will make it so that all three of the friends live, and I think I know which one will die.
My first choice would be Harry, but seeing as how these books are blatant statements about good triumphing over evil, I find his death hard to see. Another reason why I don't believe it would be Harry is because Harry is not returning for his seventh year. This is significant because though it seems JKR will not write anymore Harry Potter books after the seventh, the fact that Harry is out on his own now leaves the possibility to write another book about him open ( but although I nixed his death as a possibility, deep down I still think he should snuff it).
I have a strong feeling that the person to die will not be Hermione. This is because her intelligence is what assists Harry in finding out what he needs to know about many things. Hermione's smarts are key in helping Harry find the other Horcruxes as well, therefore, I do not believe that she will die.
In the seventh book, Ron will be the one to die. I feel strongly about this because JKR says that Harry will be stripped of the people he loves most (i.e. Sirius, Dumbledore) because he needs to do things on his own. While this might be an argument for Hermione being the one to die, I continue to dispute this argument because regardless of how she helps him, Harry always, always finds things out for himself. Anyways, as I've said, Ron will die. Harry and Ron have been the closest friends out of the Trio, if even by a little bit, and Ron's deaty, I believe, will hurt just a little more than Hermione's. Ron and his family took Harry in, and Ron always took Harry's side in arguments with Hermione. In general, Ron is Harry's best friend and I think that his death would signify the tragedy and sorrow that Harry is experiencing, as well as play the role of the impetus that Harry needs to finish off Voldemort.