I see it as a territorial thing. Michael owns the rights to the song (beat Paul in price), and though he sings the four verses where John describes each of the beatles, Michael uses the chorus to say he's taking it one step further. The world and his fans must and will come together "over him", over not his dead body but his live one!! In the movie Moonwalker he disappears causing grief to the 2 kids, but then he returns much to their joy. Come together is what he sings to show especially the actor kids. Maybe it represents the coming real concert he will do for the world and especially his own 3 kids who have never seen him actually perform in a live concert only the rehearsal. I think in the old MJHD site there was discussion on this, that Sean who is John's son was Michael's choice for the boy in Moonwalker, and the girl, seemed a lot like Paris now, protective of her Daddy. Maybe someone remembers more from that discussion.