Ok, it seems our protagonists have a last wild card for the very end. ;)
Tv show didn't mention Valonqar and Cersei's end coming by "his" hands, I suspect D&D to change things. At first I thought they did
it in purpose,because othervise tv audience would be spoiled by the end of Cersei's storyline. You know,if they add Valonqar to her prophecy everyone was going to know that Cersei has plot armor until all of her children are dead.
But then I thought maybe they are going to use a female character for the job?
According to this,Cersei managed to eliminate all her enemies including Daenerys (thanks to the great threat in the North, the task was not that hard).And the worst thing in war might be people knowing their leader fallen down, right? People shouldn't know,so Arya takes her role after she died.After all, she admired her as soon as she heard Daenerys' "Break the Wheel" speach Vol.2.By this, Arya revenges her father,her mother,her brothers and her unborn nephews.