I don't know what to say about this but if you try to analyze A has been caught inside the personality of Mona. So what did you think? is that not the real A? Maybe there is a possibility since after she was there to pick up the line, a new devastating message send to our main characters and I believe that Maya can do something to that base on her situation.
We should fix our mind in our investigation along with not the real A, maybe there is a new A on Pretty Little Liars Season 3? what do you think? of course there is no point to watch the new season online without enemy. Such a boring TV series but that is the why we are so excited although Mona has been prison. There is new crime to solve.
Aside from new A, I'm also thinking that Alison is still alive and she with the girls, her friends, new colleagues or other people who can do her intention for her. It is really easy to get new characters maybe some of their closest friends, because it is really hard to determine the truth if they have lots of secrets and only Alison knew it. They trust their old friends more than any other. From the start this is their suspect but no evidence, just text messages, threat and the moment of truth.
If you have time you will see on Pretty Little Liars Season 3 Episode 1 that they are working together to solve their new enemy, bit challenging for those who are still thinking that Alison can do it. Now what is her purpose. It is possible that she has some grudge with the four girls and it is easy to take revenge if they are friends and that is what she did and possible to do along on her death, vengeance granted.