While NBC has confirmed the worst-kept secret in show-biz—that Jimmy Fallon is officially replacing Jay Leno as the host of the Tonight Show—over on CBS, some Hollywood insiders say that David Letterman could be on his way out. The long-time Late Show host’s contract expires in 2014, and some TV industry-watchers believe it would be the perfect time for the network to secure their own new late night personality: Daily Show host Jon Stewart. They also point to the fact that CBS is owned by Viacom, who just happens to also own Comedy Central, the network that airs Stewart’s nightly comedy show … Discuss