My guess: Zimmerman will either be charged with manslaughter or more probably, second degree murder.
From a Miami lawyer’s website.
FL Second degree murder
“The unlawful killing of a human being, when perpetrated by any act imminently dangerous to another and evincing a depraved mind regardless of human life, although without any premeditated design to effect the death of any particular individual, is murder in the second degree and constitutes a felony of the first degree, punishable by imprisonment for a term of years not exceeding life.”
“The killing of a human being by the act, procurement, or culpable negligence of another, without lawful justification according to the provisions of chapter 776 and in cases in which such killing shall not be excusable homicide or murder, according to the provisions of this chapter, is manslaughter, a felony of the second degree.”