I quit watching late night when Carson retired
A lot more quit when Jay Leno retired. That's why Jimmy Fallon for a LONG time harkened back to the original Steven Allen 1950's Tonight Show style (and became pretty successful at it).
I do think that Colbert has been quietly "put on notice" regards to his material. What worked on the cable-only Colbert Report on Comedy Central doesn't work on The Late Show on CBS.
I watched a few shows of that idiot who used to be on Seebs, but he was so boring that I stopped watching