He announced the date of his last show last night. From the Hollywood Reporter...
The date for his final show will be Thursday, Dec. 18. Colbert made the announcement on Thursday's show, as part of a pitch for the paperback release of America Again: Re-becoming the Greatness We Never Weren't. "Stephen Colbert, the guy you've seen here every night for nine years will be gone. All you'll have left of me is this book," Colbert said holding up the paperback. "So pick up America Again in paperback for a loved one. Or for a hated one. Go to your local independent book store, because I have a longtime war against Amazon, and I will never relent. Or — buy it on Amazon, because, you know, just buy it."
I can't wait to see what kind of a show he'll be doing on CBS. Will he be able to do a more mass appeal show? That's the (many) million dollar question.