This scenario was tossed out a few times, usually with the assumption that racism was behind the Martin shooting and with the immediate supposition that Zimmerman would have been tossed in jail and never heard from again to the cheers of all the "racists" that applaud the Zimmerman verdict.
Interesting fact: that scenario did play out. Sure, there are some differences. You'll never see the exact same situation occur again with races reversed*. What happened?
http://themartialist.net/?p=306
A black man confronts a couple of white teenagers after calling 911. He purposely took his gun with him to the confrontation. He engaged in the confrontation because he was afraid the teenagers would get away. One of the teenagers charged at him and was shot twice and died. Scott was charged with manslaughter and, like Zimmerman, was found not guilty.
* Here I accept for argument's sake that Zimmerman can be considered white.