John Coltrane has been gone so long, and has grown to such mythic status, that it's hard to believe that he would have only this weekend been turning 80 years old. That's younger than Marshall Allen, still leading the Sun Ra Arkestra, and Von Freeman, still blowing up a storm in Chicago, just to name two. There's no way to tell what Trane would have done in the intervening decades — no one stays forever as consistently innovative and searching as the tenorist was at the end of his life. That his legacy was cut off so abruptly is in a way its power; the always questioning Coltrane left his own question mark, which generations of jazz musicians have been trying to answer. Several of them will gather in Trane's hometown this weekend for a two-stage festival celebrating his life, headlined by an all-star band featuring tenor disciple Archie Shepp (pictured) and pianist Stanley Cowell.