Jay Leno is no laughing matter for NBC

Less than a month after Comcast's (CMCSA) NBC denied a report in the Hollywood Reporter that it was prepared to replace Jay Leno as host of "The Tonight Show" comes a detailed story in The New York Times indicating that's precisely what's going to happen.

According to the Times' well-respected TV writer Bill Carter, NBC has promised the "Tonight Show" job to Jimmy Fallon and is even prepared to spend big bucks to relocate the show to New York City from Burbank, Calif. The switch, according to Carter, will take place by the fall of 2014 at the latest.

This is a huge gamble for Philadelphia-based Comcast for many reasons.

Getting rid of Leno may not be easy or cheap. Although his contract doesn't expire until next year, the relationship between the veteran host and NBC continues to deteriorate. Things may get even more awkward as NBC tries to negotiate a new deal with Fallon, the host of "Late Night With Jimmy Fallon," and create a graceful exit for Leno, who may ask for and get big bucks to leave the stage early.

The 62-year-old Leno remains quite popular, even though he isn't the favorite of some comedy mavens such as Jimmy Kimmel. And there's no guarantee that Fallon's audience will follow his move to "The Tonight Show," either.

As the network itself noted in a well-timed press release, Leno has delivered bigger audiences in the 18- to 49-year-old demographic coveted by advertisers than CBS' (CBS) "The Late Show With David Letterman" and has beaten "Jimmy Kimmel Live" for eight of the 10 weeks they have competed head-to-head in the same time slot.

The problem in advertisers' eyes is that Leno mainly attracts the wrong crowd. His overall audience has an average age of 58.1, way too old for youth-obsessed Madison Avenue. Marketers want to reach younger viewers whose brand loyalties are thought to be not as established as those of older ones.

Letterman has the same problem because his audience has an average age of  57.5. Kimmel's fans are comparative spring chickens averaging 54.1, while Fallon's audience averages 52.6.

Where are the much younger viewers? On cable. Jon Stewart and Stephen Colbert on Viacom's (VIA) Comedy Central attract viewers in their late 30s and early 40s. The audience for Chelsea Handler on Comcast's E! averages 35.

If NBC botches Leno's second departure, it risks another public relations disaster. Many of Conan O'Brien's viewers never forgave NBC for pushing the red-haired comic out the door in 2010 to bring Leno back to "The Tonight Show" after his prime-time show flopped.

O'Brien's current bosses at TBS, which is owned by Time Warner (TWX), were pleased enough with his ratings to extend his contract for the "Conan" show last year. O'Brien may have the last laugh in Leno soap opera: At 35 years old, his audience is the youngest in the late night crowd.

Jonathan Berr does not own shares of the listed stocks. Follow him on Twitter @jdberr.

More on moneyNOW

• Hungry for a hit, McDonald's adds McWraps

• Monster Beverage looks for a buzz from food stamps

• What recovery? Many workers still stuck in recession