Traditionally, one must attempt to retreat before one is justified in using deadly force against a potential assailant. There are other requirements, too, such as a subjective belief in the imminent danger of grievous bodily harm that is not objectively unreasonable, and battlefield mercy rules (once the assailant is down and apparently incapacitated, don't finish him off!). In the last thirty years or so, some jurisdictions—including Florida—have begun relaxing those rules whenever one is defending one's dwelling. These relaxations have almost always included eliminating the retreat requirement. The Florida Senate, according to the article, has now proposed eliminating the retreat requirement in public places, too.
Like I said: Dodge City. Not living there myself, I don't know if that will make much difference; it sure wouldn't have outside the front gate at my last base shortly after Gulf War I. We were completely unconcerned about terrorists trying to shoot their way into the base: They would have been outgunned by the locals if they had anything short of a T-72.
In any event I predict that the real action in street-shooting cases is going to turn not on retreat, but on the objective reasonability of fear of grievous bodily harm. This is no doubt going to ratchet up racial tension, as both sides play the race card in intricate gambits to inflame the jury's passions.
<SARCASM> Of course, if Florida hadn't already held the rest of the nation hostage with a flawed election process twice in the last five years, I might be more willing to ascribe this to local peculiarities. </SARCASM>