Good Lord, would she have to testify????? "Ms. Anthony, have you ever told a lie? Ans: No." lol
Well, she could always answer, "Yes," followed by, "See, I'm not a liar."
Seriously though, if the appeal is claiming she was not properly Mirandized and there is any evidence that puts that into question, she might win a new trial. And I am not sure the state would retry, due to budget concerns. We all must brace ourselves here for the fact that she may slide on the only charges she was actually convicted of.
But take heart because, when all is said and done, it won't matter. Casey will have her comeuppance.