On Tuesday, Diane Sawyer was on stage with Whitney Houston before a crowd in Central Park. On Wednesday, she was crowned the leader of ABC's network new division. Sawyer, the longtime co-host of ABC's 'Good Morning America,' was named the successor to Charles Gibson, who is stepping down as the anchor of ABC's 'World News.' ABC announced the moves on Wednesday; they will be effective in January. The arrival of Sawyer will comprehensively alter the long-established image of an avuncular male nightly news anchor. With Katie Couric, who took the CBS anchor position in 2006, two of the three main network news voices will be female, a role that has punished others, like Barbara Walters and Connie Chung, in the past. 'You're going to have, for the first time ever, two women competing as solo anchors in a television framework that just -- within living memory -- sort of destroyed every woman who tried to do it,' said Richard Wald, a former news executive at ABC and NBC. For Sawyer, the promotion is the culmination of years of waiting. She took the morning job on a temporary basis, then stayed for 10 years, reviving ABC's morning franchise. But was passed over twice for the evening anchor job. Her wait came to an abrupt and unexpected end when Gibson, 66, announced his intention to step down. David Westin, the president of ABC News, characterized the decision as entirely Gibson's, after the two men held conversations that extended through the summer. The decision was sudden enough that ABC does not have a plan in place to replace Sawyer, who is 63, on 'Good Morning America,' which is by far the most profitable program in the news division and where she is by far the biggest attraction for viewers. One executive estimated that it brings in about $50 million a year for ABC. Neither Gibson nor Sawyer would give interviews about the moves Wednesday. Both issued statements instead. ABC News executives said the choice was inevitable, both because Sawyer had expressed interest in succeeding Gibson whenever he stepped down and because she was the most prominent name in the news division. 'Diane was the obvious choice,' Westin said. 'She always said this was Charlie's time, but yes, she always expressed interest in the job.' 