The prophecy says that Cersei will be killed by a younger brother ... could be Tyrion, could be Jaime (who was born after Cersei) ... could be Sandor Clegane.
The writing is on the wall. Without any prophecy it’s obvious that Cersei will kill Jamie or Jamie will kill Cercei. (Or they die together at the hand of another).
The most likely being Jamie kills Cersei, as he recognizes the woman he loves is absolutely insane and evil. They may love each other, but her actions killed far mor than just their enemies and cost them their final child as well. My guess would be when the city is about to fall to its enemies Cersei will want to blow the whole thing up with wildfire and Jamie will kill her just as he did the mad King.
Then I would agree that it is a good possibility that Jaime will be the one. He knows what she did to the Sept, and he killed the King who was going to the same to the whole city. Cersi has that insanity in her, and Jaime might have to be a “Kingslayer” (Queenslayer) again.