So, this took far longer than it should have, but I enjoyed it. I bolded the free agents following this season, but like I said, NASCAR contract details aren't as public as other sports. Also, didn't include part-time drivers since that information is even harder to find.
#1: Ross Chastain-Signed through 2025
#2: Austin Cindric-No contract details available, but no indication that he won’t be with Penske
#3: Austin Dillon-No contract details available, but reports say he signed a multi-year extension…and his grandpa owns the team.
#4: Josh Berry-Just announced that he’s replacing Harvick. Haven’t seen contract details
#5: Kyle Larson-Signed through 2026
#6: Brad Keselowski-No contract details, but he owns part of the team.
#7: Corey LaJoie-Free agent after this season
#8: Kyle Busch-No contract details available, but no reason to think he’s going anywhere.
#9: Chase Elliot-Signed through 2027
#10: Aric Almirola-Could be retiring at the end of this season after planning to after last season. This is the last year of his contract, so this ride should be available.
#11: Denny Hamlin-Free agent after this season, but says he wants to stay at JGR. Worth noting that 23XI’s contract with Toyota expires after this year. Hamlin has said that he can’t drive for Toyota while owning a team that races another manufacturer. His contract is totally contingent on 23XI getting a deal done to stay with Toyota.
#12: Ryan Blaney-Conflicting information out there on this one. Some sources say his contract is up after this year, while others have it ending after 2024 and even 2025. Doubtful that he leaves Penske, and even harder to guess since we don’t know his contract details.
#14: Chase Briscoe-No contract details available. Jayski has his deal running through 2026, while Sportrac says it ends after this season.
#16: AJ Allmendinger-No details available, but it’s expected that Dinger returns to the 16 next season.
#17: Chris Buescher-Signed a multiyear deal in 2022, and it’s expected that he’ll be back next season. Fastenal, the primary sponsor, is signed through 2024. Has some good results this year. Some reports also said that Keselowski bought into the team because he really believed in Buescher, making it even less likely that he's gone.
#19: Martin Truex Jr.-Free agent after this season and has discussed retirement. If he comes doesn’t retire, will likely be at JGR.
#20: Christopher Bell-No contract details available.
#21: Harrison Burton-Free agent after this season. Underperformed last year and is statistically worse this year.
#22: Joey Logano-Signed through 2025
#23: Bubba Wallace-He’s either signed through 2024 or 2025.
#24: William Byron-Signed through 2025
#31: Justin Haley-Free agent after this season.
#34: Michael McDowell-Free agent after this season
#38: Todd Gilliland-Free agent after this season. Zane Smith is (or has) driven the car in 6 races in 2023.
#41: Ryan Preece-Free agent after this season. Apparently, SHR planned on possibly losing everyone after this season, and with their results…who could blame them?
#42: Noah Gragson-Free agent after this season
#43: Erik Jones-Believed to be signed through 2024 after signing a multi-year deal in 2022.
#45: Tyler Reddick-Believed to be signed through 2024 after joining 23XI this season.
#47: Ricky Stenhouse Jr.-Signed a multi-year extension in 2023.
#48: Alex Bowman-Signed through 2026
#51: Cody Ware (and some other people since he’s been suspended)-Ware’s Cup career is probably over, even though it’s his dad’s team.
#54: Ty Gibbs-No contract details available, but his grandpa owns the team.
#77: Ty Dillon-Free agent after this season. Worth noting that Spire is an affiliate of RCR…so Grandpa probably has a lot of say in whether Ty comes back.
#78: BJ McLeod (with Josh Bilicki and Anthony Alfredo)-McLeod is a co-owner in the team, so it’s unlikely that there will be any movement.
#99: Daniel Suarez-Signed through 2025
TL;DR:
LaJoie, Almirola, Hamlin, Truex, Burton, Haley, McDowell, Gilliland, Preece, Gragson, Ware, and Ty Dillon are all slated to be free agents after this season.