“Since the Valonqar is Valyrian for the ‘little brother’, most people think that Jaime, or maybe Tyrion, will kill Cersei.
The Valonqar means ‘the little brother’, not Cersei’s little brother.
Consistently called ‘little brother’ by Cersei, has plenty of reasons to want to kill her himself, and has already made a habit out of killing Lannisters.
I think that in a show as unpredictable of Game of Thrones, this is too obvious.