In February, Fallon signed a developmental deal with NBC that included the possibility of
replacing O'Brien. Now, some people familiar with NBC's thinking say the network believes the pair of Fallon and O'Brien would be a compatible two-hour block. NBC has not done any run-throughs with
Fallon, but Ludwin is confident he has seen enough of Fallon's talents from "Saturday Night Live, "which included hosting the "Weekend Update" segment. And Fallon also served as guest host for David
Letterman's in 2003.
"These are very tough jobs when you promise comedy as part of the equation, and it's a grind to do one of these shows," Ludwin says.