I personally believe nothing would have happened at all, echoing this:
As Dibble said in the other thread: No watchman, regardless of race, would question a white boy walking around a gated community.
And if the altercation still did happen, it probably would have been like this:
No one would care because the case would have never garnered enough attention to make it a national story...
Black Zimmerman wouldn't have been allowed to just go home, he would have definitely been taken back to the police statiion and they would have crossed every T and dotted every I from the beginning. The media only got interested when that wasn't the case.
I think it would have been more likely for him to get the manslaughter charge but I wouldn't be surprised if he still got off.
I like the question of swapped races here, hence why I posted the thread with that picture, because it's very interesting how people with different viewpoints interpret it totally different ways.