Playboy and Penthouse once defined the adult genre. Now, they’re now fighting to stay relevant. Hardcore porn, accommodating almost any taste, is available on video tape and cable television, a mere remote click away. Hefner and Guccione are facing the inescapable vagaries of getting older in a young man’s game. Sex industry rivals are coming and they’ll be followed by even bigger guns. But the aging warriors aren’t surrendering yet.