NEW YORK - Jimmy Fallon's fast start replacing Jay Leno on the "Tonight" show the past two months had a secondary effect: David Letterman suddenly seemed old.
The Top 10 list, the ironic detachment, even the set at the Ed Sullivan Theater. Time doesn't stop for comedy legends, or superstars of any sort. Letterman, who announced Thursday he will retire from late-night television sometime in 2015, had to feel it.
CBS now faces the challenge of moving on in a reordered late-night world at a time the two Jimmys - NBC's Fallon and ABC's Kimmel - have a significant head start.
When Jay Leno left in February, Letterman lost his foil - the man whose victory in the competition to replace Johnny Carson two decades ago he never let go. Leno was someone who spoke his language, though, a generational compadre, and when he left, Letterman was alone.
Fallon and Kimmel have a different style, more good-natured and less mocking of the entire concept of a talk show.
The first time Leno left late-night, Letterman ascended to the throne. Not this time. Since Fallon began at "Tonight," his show has averaged 5.2 million viewers, while Letterman has averaged 2.7 million and Kimmel 2.65 million, the Nielsen company said. Last year, Letterman averaged 2.9 million and Kimmel 2.5 million, so the direction was clear.
Much of late-night now is about making an impression in social media, or in highlight clips that people can watch on their devices and spread around the next day. Fallon and Kimmel have excelled in spreading their comedy beyond their time slots; Letterman barely has bothered.
Late-night television is a far different world than when Letterman and Leno began their competition. There are more entertainment shows to choose from, with personalities such as O'Brien, Arsenio Hall, Jon Stewart, Stephen Colbert and Chelsea Handler working every night.
CBS will first have to decide whether to continue with an entertainment program in that time slot. It's not the money-maker it once was, but chances are the network will continue in that direction.
The first in-house candidate would be Craig Ferguson of "The Late Late Show," which currently airs at 12:35 a.m. on CBS and is produced by Letterman. But Ferguson's star has dimmed, his show quickly passed by in the ratings by Seth Meyers on NBC, and he is considered an unlikely choice.