According to Ian Harding (Ezra Fitz), the revelation of "A"'s identity won't be the most shocking thing that happens in the finale.
"["A"'s identity] is not even the biggest part of the episode," Ian explained, adding "there must be something huge in this finale if revealing who ‘A’ is isn’t the biggest shocker." Similarly, Tyler Blackburn (Caleb Rivers) promised that "once 'A' is revealed, there’s another mystery [that] kind of starts from that."
It's hard to imagine what could be more shocking than finding out who "A" is, but, just for fun, we're going to try to guess. Read our theories, and then share your own!
Alison is alive: Think about it. Ali (Sasha Pieterse) being alive would be a huge twist. It would also fit with producer Lisa Cochran-Neilan calling the episode "heartbreaking." Finding out their dead BFF isn't so dead after all would definitely throw the Liars through a loop, and would open up a lot of questions for Season 3 to explore.
We also find out Ali's killer — and it's someone close to the liars. The identity of Ali's killer could be even more shocking than the identity of "A," not to mention heartbreaking, especially if it is someone close to the liars, like a parent (*cough*Spencer's [Troian Bellisario] dad*cough*).
"A" isn't working alone. What if the girls uncover "A"'s identity, and it looks like everything is going to end well and then — BAM, they get another text. It could start the whole cycle over again.
A new murder mystery crops up. Promos have been promising that someone will die all season. It's possible that the death will come about during the hunt for "A," but what if it happens separately, starting a whole new mystery? Depending on who dies, this could definitely be heartbreaking.