It can happen a number of ways. Cersei hasn't even had her trial yet in the books. She isn't going to become queen like she did in the show. The show made her the main baddie because they didn't want to write Aegon into the story so late and because they like Lena Headey so much (hell, they ain't paying her a million an episode for nothing).
Some speculate she might even lose her leg like Jaime lost his hand, because she walked through a bunch of shyt during her walk of shame and her feet are all bloody by the time she gets to the red keep. I think we've already seen her best days in the books.