What happens after the final sentence of Song of Solomon?

Toward the end of the text, Milkman has brought his aunt, Pilate Dead, to Virginia to bury her father's remains in his home. Suddenly, Pilate drops to the ground and Milkman hears a gunshot; Guitar had fired the gun, apparently aiming for Milkman. Pilate asks Milkman to watch over Reba, her daughter, for her. Birds swoop down and carry the earring with her name in it into the sky. Milkman turns to face Guitar, asking, "'You want my life? . . . You need it? Here,'" and without any preparation at all, he leaps at his former friend. The narrator says that it does not matter which of them dies, because

For now [Milkman] knew what Shalimar knew: If you surrendered to the air, you could ride it.

In this way, the author has included some intentional ambiguity. We do not know if Milkman lives, or Guitar, or neither. The speaker says that this is not truly the important part anyway. Earlier in the novel, Guitar said that in order to "fly" a person has to give up the stuff that weighs them down: greed, vanity, and so forth. Milkman has, evidently, given up all this stuff. We have seen him ruin his nice clothes, lose his gold watch, let go of his selfishness and materialism. He has taken responsibility for Hagar's tragedy and death; he has learned to rank others' needs with his own rather than putting his own needs first and failing to acknowledge anyone else's.
It is possible that Milkman kills Guitar, and it is possible that Guitar kills Milkman; however, I think it is possible that both men die. For Milkman, death would seem less tragic, as he will die having learned how to "fly," and this seems to represent the height of enlightenment: Pilate could fly, and she seems to be the most loving and generous and not self-centered character in the text. For Guitar, on the other hand, death would be more tragic, because he has not reached this kind of understanding of himself and the world. Morrison leaves it open, so we do not know exactly what happens after this last line. This gives us a lot more to talk about, though, doesn't it? We can weigh the possibilities and consider the consequences of each one rather than only discuss the one committed to paper.