Unlike NBC, with its Tonight Show host training camp (aka SNL) and clear heir apparent in Jimmy Fallon, CBS does not have as evident a line of succession for David Letterman‘s late-night throne — though Craig Ferguson hosts CBS’ other late-night program which, like Late Show, is produced by Letterman’s Worldwide Pants (it’s now a co-production with CBS). He has a succession clause in his contract, but that contract is set to expire this summer. Presumably, he’d seek the same in his next contract. Should CBS balk, the network might find itself looking for two late-night hosts within months of each other — which would be tough, and not the image of stability CBS has so carefully cultivated. Additionally, Ferguson has won a Peabody Award for his show and has hosted the White House Correspondents’ Dinner, and that kind of prestige appeals to Moonves. Regardless, almost immediately after Letterman announced on his show tonight he’s stepping down sometime in 2015, The Reporters Who Cover Television began playing The Replacement Game. Comedy Central’s Stephen Colbert name keeps popping up; he’s said to be well-liked by CBS Corp. CEO Leslie Moonves and, with his contract coming up in mid-2015, Colbert could be available if his network does not sign him to a new contract by the time Letterman bows out. Ditto Comedy Central’s Jon Stewart, whose contract also is set to expire at around the same time and who, years ago, was under option at CBS as that network was looking for a Late Late Show host – CBS went instead with then-Daily Show host Craig Kilborn. (Ferguson won the companion-show gig, from a slew of auditioners, after the network threw in the towel on Kilborn.) Some sources speculated the April Fools’ Day job-swap of Ferguson and CBS’ Price Is Right host Drew Carey might actually have been Carey’s first late-night audition at the network. Others on the list are known to be looking for employment elsewhere – like E!’s Chelsea Handler, who has said her show will be toast at the end of the year because the network has become a “sad, sad place.” Another name that popped up this afternoon: Neil Patrick Harris, the versatile How I Met Your Mother star who has demonstrated a knack for talk shows when he sat in with Kelly Ripa on her syndicated daytime talker and is highly regarded at the network for his stints hosting the Tony and Emmy Awards. And don’t forget Louis C.K., who during the third season of his FX series was offered a chance to take over Letterman’s show by the head of CBS (played by Gary Marshall) — until everything goes wrong for Louie, and Letterman re-ups for 10 years and declares his wannabe replacement persona non grata.