Seth Myers does a regular Daily Show type item, then you've Colbert doing very topical monologues.
Although, to be honest the 'A Closer Look' feature in Late Night With Seth Myers, owes far more to the first section before the 'And Now..This' on Last Week Tonight with John Oliver. Right down to the framing and the location of the over the shoulder box graphic.
I doubt CBS would want to drop Colbert totally - they've spent a heck of a lot on the roof to basement renovation of the Ed Sullivan Theatre post Letterman to just let that go to waste.
Moving him back to 12.35, and letting him be a bit 'looser' will let them go for the 'chat show anarchy' vibe that Letterman nailed during his 16 years on Late Night on the peacock network. Plus, it'll allow Stephen to go more on the satirical/political gags, without the fear that the core CBS audience isn't shuffling on their sofas, not laughing at an in-joke aimed at the White House Press correspondents, and hoping the interviews start soon.
Course, the problem was CBS were almost in a no-win situation from the off.
Mostly, Colbert was not David Letterman.
Second, he really became famous playing a overblown character parody of himself - and it takes a lot (even for his fans that followed him across from Comedy Central) to accept that even without the shouting and finger pointing in the monolouge - it was Stephen Colbert playing himself. I knew the show was starting to look for an on-line sharing spark, when John Stewart turned up earlier this year, to deliver a 'hands crossed on the desk' piece to camera taking apart Fox News - just like the good ol days on The Daily Show.
Third - Whilst I could see the need to hit the ground running with the new style of 11.35 show, your audience at that time (like at the other end of the day) likes what it likes, and wants to see that night after night.
Switching Corden around to 11.35 may also have another hidden undercurrent behind it. Yes, he'll appeal to the 'You Tube/Twitter/Facebook' share this generation (something that Fallon, it's been mentioned mined very well, very early on) but since Fallon started The Tonight Show, there's only one before midnight show coming out of the West Coast - and I just wonder, if the big Hollywood cleb bookers are starting to give NBC/CBS a bit of heat over this.
Probably a good scheduling move - although how long before he hear stories of CBS looking around and auditioning people ready to jump into the 12.35 slot, if Colbert bombs in that slot, and is moved to Showtime (if only to give the Ed Sullivan theatre crew something to do) or just takes the $20million payoff cheque?
My user name might look like Hatton Cross, but it's pronounced Throatwobbler Mangrove.