What will Harry do after Hogwarts?

I think your's is a good theory. After all the emphasis in the books on the ever changing dark arts teachers it would seem to fit that he would end up becoming it in the end. Unless of course he succeeds Dumbledore as headmaster and runs Hogwarts, with Hermione and Ron as teachers with him (if of course they were to live) but who knows. Im sure there will be twists that we cant predict.