The big news in network news is the passing of the torch. Late last year, 21-year veteran Tom Brokaw stepped down from NBC Nightly News. And now that General Electric (NYSE:GE) unit NBC Universal has said goodbye to its anchor, Viacom's (NYSE:VIA) own elder statesman, Dan Rather, is preparing to leave CBS Evening News in March.

NBC had long prepared for its transition, even going so far as to have Brokaw's replacement, Brian Williams, share the broadcast. But CBS's intentions still seem up in the air, at least based on comments from CBS Chairman and Viacom President Leslie Moonves at a recent news conference.

Moonves is apparently considering all kinds of changes to the look and feel of CBS's nightly news. Options reportedly include using multiple anchors, hiring Katie Couric of NBC's Today show, and even bringing in Jon Stewart, the star of Comedy Central's The Daily Show. The underlying idea, Moonves indicated, is to go for a younger crowd.

Although innovation is a good thing, one has to wonder whether it's wise to tinker too much. Sure, cable news outlets such as Fox Entertainment's (NYSE:FOX) Fox News Channel and Time Warner's (NYSE:TWX) CNN have nibbled away at the networks' viewership. But network news, whose audience share fell by 23% between 1993 and 2001, has done a better job hanging onto its viewers than have the networks themselves -- their audience plunged by 42% over the same period, according to the Project for Excellence in Journalism. What's more, CBS Evening News remains a cash cow: For 2003, the program was projected to have generated $159 million in revenue for parent company Viacom.

The nightly news broadcasts may indeed need some updating. But to paraphrase Brokaw, one of their advantages is that they give the impression (and maybe it's just an illusion) of a single source of authority amidst a cacophony of media voices. Katie Couric may be likeable, but that likeability may not translate when she's delivering hard news rather than the human-interest and entertainment stories that are the norm on the Today show. And Jon Stewart is a funny guy, but putting a fake newsperson on a real news show could be an exercise in self-mockery. Viacom would be wise to proceed cautiously when changing CBS Evening News.

Fool contributor Brian Gorman is a freelance writer in Chicago. He does not own shares of any companies mentioned in this article.