We're not sure we ever actually thought consciously about a time coming when David Letterman wouldn't be doing The Late Show.  But recently, thank god, Letterman said he's still got a few years left in him, so we won't have to revisit this thought for a while.  

"The way I feel now, I would like to go beyond 2010, not much beyond, but you know, enough to go beyond. You always like to be able to excuse yourself on your own terms," Letterman said in an interview in Rolling Stone magazine.

The thing is, we've spent our entire lives with David Letterman as a constant fixture of late night TV (either on Late Night or Late Show), and we don't like to even imagine a time when that won't be true.  Don't go David, we can't abide the thought of another TV host mainstay of our childhood being replaced by some sitcom actor (We miss you, Bob Barker).