Harry is the last horcrux, his scar marking out to Voldemort maybe, so he -has- to die. Part of me would like to suggest Harry gets Ginny pregnant and so lives on in spirit, but Fawkes’ll probably resurrect him or something. And Ginny won’t get pregnant. Snape will have had an Unbreakable Vow with Dumbledore the entire time, hence D’s never faltering trust in him. Snape will be killed.
That’s all.