I still believe she will not be called to testify. Her use was for probable cause only, otherwise why didn't they include more details or even a transcript of what she heard in the affidavit? All they stated was that "some friend was on the phone with him and he said he was scared about 4 minutes before the shooting." If she does testify, I don't see her testifying to much more than just that, "Travyon was scared about 4 minutes before he was shot." I could be wrong on both, and if I am, being that she's an ear witness she can't attest to the events that happen, only what she heard. What did she hear? Well, skipping over most of the conversation, she heard "Why are you following me?", "What are you doing here?", "Why are you fo-'hiccup'-llowing me" ... that "hiccup" is where she states that she thinks Mr. Martin was pushed. She can't testify to exactly what that was because she doesn't know, she just thinks that something happened.
However, as I stated in my first sentence, I don't believe she'll be called to testify because Investigator Gilbreath did state, as a matter of sworn fact, that he had no evidence to contradict Mr. Zimmerman's story regarding this. Why would he commit perjury?
* Time estimations are my own, with nothing reliable to back up the "4 minute" estimation that I gave. Example only, basically.