https://www.cnet.com/news/the-walking-dead-reveals-3-returning-characters-for-season-9-at-nycc-2018/

"There were some rumors going around … we were trying to lie, but we want to confirm that Jon Bernthal is coming back," showrunner Angela Kang said during the NYCC panel.

But since Bernthal's character died, was turned into a walker and then was killed again, chances are he'll probably return in a flashback memory moment.