When Stephen Colbert ends The Colbert Report sometime later this year in order to take over as the new host of David Letterman's The Late Show on CBS, it will necessitate the first major change in Comedy Central's late night original programming lineup in almost a decade. As a double-act, Colbert and his lead-in of the Jon Stewart hosted Daily Show have defined a generation of political comedy and an emerging post-Nielsen generation of TV powerbroking whereby ratings (Stewart and Colbert are routinely outgunned by competitors like Adult Swim) are often viewed as secondary to next-day news coverage and social-media impact, where they dominate.
Unlike Daily, which didn't really find it's groove until Stewart took over for original host Craig Kilborn and reoriented it to a news/politics focus, The Report is bound up almost entirely in Colbert's Fox News caricature alter-ego. While there's been no official announcement as to the fate of the show and/or its timeslot, it's almost a foregone conclusion that an entirely new show will have to take its place, as opposed to simply changing out hosts.
With that in mind, here's a few ruminations on who and what might, conceivably, make a suitable replacement - operating from the (likely) premise that Comedy Central would seek a similar show to preserve the Colbert/Daily audience and prevent a bleed to other hour long 11:30pm shows - which could be disastrous for the ratings of other shows like Chris Hardwick's @Midnight.