NBCSN will cease programming on December 31st. Most of the live sports will move to USA network in 2022.
The last thing they show will probably be either an infomercial or a car auction.
You guessed it, lol
The last regularly scheduled program is a rerun of Mecum Auto Auctions, followed by a block of Infomercials, and then at 6am on New Year's Day a slate advertising the sports moving to USA. Although many cable and sat providers will likely take down the channel early and replace it with their own custom slate. (i.e. When Chiller ceased on 12/31/17, DirecTV took it down mid-movie at around 5:30pm instead of leaving it up until the midnight shutdown)