The top producers of ABC News’ flagship programs are getting new roles. Good Morning America senior exec producer Tom Cibrowski has been promoted to SVP ABC News Programs, News Gathering and Special Events. He will be replaced at the top-rated morning program by Michael Corn, executive producer of World News With Diane Sawyer, which is in its final week.  Almin Karamehmedovic, who has been running Nightline, has been named executive producer of World News With David Muir, which will launch after Labor Day.