Celebrity Dave's Seat Being Filled? By People Staff Published on November 9, 1998 12:00 AM Share Tweet Pin Email Talk is heating up around the stages of “Late Show.” CBS reportedly may bend after all and allow a substitute host to sit in for David Letterman while he recuperates from heart surgery. “Who Wants to Be a Millonaire”‘s hot host Regis Philbin has offered to fill in for Dave, Letterman’s producer Rob Burnett has told reporters. (Regis also costars with Kathie Lee Gifford on an ABC morning show.) Other celebrities are also said to have offered their services, though Burnett has not named them.