• by Wayne Friedman , Staff Writer, April 26, 2011

These jobs aren't forever, Katie Couric told David Letterman recently. That message will be confirmed this week, when CBS is expected to announce her departure as head of "The CBS Evening News" (she just announced the news herself, actually.)

Being the main anchor of a big TV news broadcast used to be akin to a Supreme Court judgeship -- you held the job until basically you couldn't do it anymore. CBS' Walter Cronkite held the job for decades; so did Dan Rather.

Couric? Just five years. We know her remarks to Letterman had a point. Those early evening newscasts aren't  what they once were.

Not that TV news executives haven't tried to change things. When Couric came aboard, CBS had been touting that its news brand would be aggressively extended -- to online, social networks and mobile devices. But has that been enough?

News producers owned up to the fact they bit off more than they could chew -- looking to make big changes, getting away from what CBS does best. Through it all -- even with some personnel losses -- CBS has still gotten its share of news scoops.

But that's not the measure of a good TV show anymore. With the fractionalization of viewers -- and news consumers going into many directions to get what daily news they need -- ratings and subsequent ad dollars mean much more. So do personalities. Even cable news has quicker changes, such as the recent departures of MSNBC's Keith Olbermann and Fox News' Glenn Beck's.

Now Couric looks to go elsewhere -- most likely to syndication. While that might allow Couric to do more of what she does best -- one-on-one interviews -- the syndication business has been no easy street.

Think about Oprah Winfrey, who is leaving after 25 years. Though she could have gone on for perhaps another couple of decades, money and afternoon viewership for syndicated shows have been tough to come by. Cash license fees for Winfrey's show and others have been on the decline for years.

It is also no picnic for any former big TV broadcast network personality to make the transition. Jane Pauley, anyone?