New York ? This may come as a surprise, but ABC’s Charles Gibson is retiring at the end of next week and Diane Sawyer will replace him as “World News” anchor. Really.

Given ABC’s stealth transition for what has been traditionally the top job in network television news, it’s understandable if many viewers don’t realize it’s coming. Sawyer has given no interviews about her new job since the change was announced on Sept. 2, and none are planned. Neither has Gibson, although he may do some valedictory interviews before his last broadcast on Dec. 18. No advertisements are planned, outside of those on ABC.

The obvious contrast is late summer 2006, when CBS trumpeted the arrival of Katie Couric at the “CBS Evening News.” And the Couric hype is exactly what’s kept Sawyer under the radar. ABC officials believe the attention paid to Couric’s move from the “Today” show backfired, leaving CBS a distant last in the evening news ratings.

The problem with Couric was that many viewers didn’t like what they saw. Couric was trying to change the mold of the evening newscasts with interviews and lengthier features, and longtime TV news watchers expecting a fairly straight rundown of the day’s events found it jarring. Couric has since settled into a harder, more traditional newscast that is widely respected. Unfortunately, many viewers didn’t give her a second chance.

CBS also faced some barriers that ABC doesn’t. Couric was the first woman given a chance to anchor the evening news by herself, something that was a real issue for a format with so many older viewers. Couric was moving to a new network after many years at NBC; Sawyer, meanwhile, is well-known to ABC’s audience.