Let me state for record that I don't read the books, only watch the shows. So just patterning how they have no problem killing off liked characters at a given moment is no stretch on the final season.
With that said I can see the last episodes with the following scenarios......
-Euron Greyjoys "present" to Cersai being either Tyrion, a dragon binder horn (a Daenerys loss), or Olenna Tyrell
-Finally learning compassion and common sense Jamie kills Cersai mad king style
-John Snow gets shockingly double crossed and killed by Sansa
-The hound (revenge) or the Mountain kill Arya in a botched assassination