Ok so I have been reading carefully and thinking about this a lot and here is my tuppenceworth.
Firstly, Cersei’s death, and the prophecy. Cersei died buried under the Red Keep. Despite my thinking she was going to tumble from the top of it with Jaime, linking it to Bran’s fall at the very beginning, instead they got buried. Which is actually OK, and cleverer than it looks, I think. Here’s why:
If you buy the valonqar theory, that says three children you will have, and lose them all and when your tears have drowned you, the valonqar shall wrap his hands about your pale white throat and choke the life from you.
She was pregnant with a fourth child but it would never be born. She was forced to watch her city burn, the tears ran down her cheeks, then crushed to death by her own palace with her little brother’s hands about her throat (sent by her other little brother!) I’m not seeing anything but a prophecy fulfilled, there.
Cersei dying down in the vaults is pretty much exactly where she would not want to be. How she hated being packed away with the women and children when war was raging, how she drank her way through the battle of the black water. How much would she have wanted an end worthy of a song, if it had to be an end? She loved Jaime. And that moment when she saw him was relived, yes it was, and well acted, but it was also pivotal because she didn’t want him to be there, not really, not for his sake. She didn’t want him to die alongside her whilst at the same time recognising that it was always going to be that they died together (as they came in to this world etc etc etc) If you were going to write an end for Cersei, and you really wanted to punish her - I’d suggest having her watch her entire city burn, know that she is lost, know that she is out-manoeuvred, and have her crushed to death alongside her brother, begging for her life, would be a good way to write it. Not to mention finding the body of the dead queen cowering in the vaults as the city burned.....