I think if it doesn't get worst for defense soon they may not put Zimmerman on the stand. They may just say you have heard testimoney from good people and its obvious there is reasonable doubt here. The one witness who said she was on the phone when it started confirmed it was Martin who profiled Zimmerman as a cracker. Then she got caught in some lies and come off as pretty street. A few jurors may find her not credible.
You never know what juries will do though but murder 2 seems like a reach.