The Miami Herald examines how easy or difficult it would be to nail George Zimmerman on a hate crime charge. Here is what a federal criminal defense attorney in Miami said: "I find it doubtful that the attorney general will pursue a prosecution on a civil rights theory simply out of displeasure with the state jury's verdict,"
Source: Miami Herald, "Federal case against Zimmerman would be difficult"
Tamara Rice Lave, a professor of criminal law at the University of Miami, tells Buzzfeed.com: “Technically, there can still be a civil case...However, ‘Stand Your Ground’ is going to preclude that.”
Source: Buzzfeed.com, "Civil Case Against Zimmerman In Florida Has Little Chance Of Success".
Frederick Leatherman, attorney, seems confident that a hate crime charge will go well against Zimmerman. The problem is that Leatherman's credibility took a hit when he disagreed with Dan Abrams of ABC News on Abrams' opinion that the jury would acquit Zimmerman of both 2nd degree murder and manslaughter. Leatherman is therefore not a very good analyst.
Source: Frederick Leatherman's post telling readers how wrong Dan Abrams was to believe the jury would do what they did. Link
In conclusion, the expert opinion so far seems to indicate that one of the two following outcomes will be true:
1) Zimmerman won't be prosecuted, or
2) Zimmerman will be prosecuted unsuccessfully.