How will Cersei's reign end completely in the books (not her death)?
Truth be told, she deserved it. She armed the Faith willingly, constantly refused to pay to the Iron Bank and attempted to stall them. She accused Margaery and tried to put a stain on Tyrell name, and she lost control of the Faith Militant almost immediately and had to perform the Walk of Atonement.
Even before that, in the previous chapters of hers in A Feast For Crows, she blows up the Tower of the Hand 'cuz she believed Tyrion was in the walls. Thought Tyrells were behind Tyrion's escape and they are trying to overthrow her (Gardener coin). It was a disaster all along. However, do you think she'll be forced to flee the capital or be exiled by Aegon the Young Griff in the BOOKS?