AOT Theory-Annie's Crystal Is Buying Her Time To Live Until Her Grand Finale(Minor spoiler)

Annie has a lot of secrets to reveal and a much, much deeper story developing for her. Well, once she gets out of her crystal cocoon. According to a theory posted by Eobard95, Annie only has a set time left to live, and being completely crystallized might be slowing down her death. If so, it's in her best interest to save her strength for a massive final fight, which will most likely be against Marley.

If the Survey Corps can convince Annie to join them, even out of anger or a desire for revenge against the people who put her in this situation, then it would prove to be a grand comeback for her.