Oh sorry TSW, I didn't mean to be obscure--I read a lot of history. In the middle ages is was not uncommon to dispose of inconvenient female relatives by having them to to a nunnery. As long as the were wealthy enough to afford the "dowry". But I must say, I don't know the rules or habits (smile) of the religious orders in Westeros.
Cersei's adversaries might also balk at the public execution of a dowager queen, widow, a regent, and the mother of kings. They may want to get her out of the way more stealthily.
Also, Cersei is well aware of the possibility, since she advises Falyse to join the silent sisters in a very odd interaction. She says "The silent sisters are always glad to welcome widows. Theirs is a serene life, a life of prayer and contemplation and good works."
Falyse does not follow her good advise, Cersei is unable to silence her that way, and so shei gets her drunk and then hands her over to Qyburn for experiments.
It's a tiny scene, but it would be interesting if GRRM was setting up a future event. The irony of Cersei in a nunnery would be just like him. It would also give Cersei time to live for her children to die and end up with their golden shrouds to fulfill the prophecy.
Maybe this is farfetched, but would you bet against it?
