In an installment of the "Late Show" that will air tonight (10:35 p.m., CBS/Ch. 2), David Letterman announces that he will be retiring in 2015.
It's a day I never thought would come. He's the longest-running late-night host in TV history, surpassing his mentor, Johnny Carson. (Carson hosted "The Tonight Show" for 30 years; Letterman will have a combined 33 years as host of "Late Night" and "Late Show.")
It's too early to write the tribute. It's even a little bit too early to start speculating about who will succeed him.