David Letterman, the CBS host who has competed with Jay Leno every weeknight for 15 years, now feels empathy for his late-night challenger.

Jay Leno’s last night on the “Tonight” show will be in May of 2009, with Conan O’Brien taking over the show a few days later.

Jay Leno’s last night on the “Tonight” show will be in May of 2009, with Conan O’Brien taking over the show a few days later.

Ben Silverman, the co-chairman of NBC Entertainment, acknowledged that the changing late-night landscape at the network would probably mean that Jay Leno would leave it.