The character of Qui Gon maybe deserves to be at the end of ROTJ, it's a good idea on paper, but really don't think it would work on the screen. You know, Luke smiling whereas it should look wondering who the hell is that new guy.
Maybe after Luke turned to his friends we can add Qui-Gon in the back of the ghosts last shot. But all in all, I don't think I'd want to see this.