Warning: SPOILERS ahead for The Walking Dead season 10 premiere.
The Walking Dead may be setting up for both Daryl (Norman Reedus) and Carol (Melissa McBride) to leave the series. Both characters have been on The Walking Dead since season 1 - they are the only remaining characters on the show from that season - so their absence would be a dramatic shift for the zombie series.
After Rick Grimes' "death" and the six-year time jump in The Walking Dead season 9, Norman Reedus was bumped up to top billing, with his character Daryl playing an instrumental role in the battle with the Whisperers. As for Carol, she lost her son, Henry (Matt Lintz), to the Whisperers. As a result, her relationship with Ezekiel (Khary Payton) fell apart.
In The Walking Dead season 10 premiere, "Lines We Cross", it becomes apparent that Carol is still reeling from Henry's death and the rift between her and Ezekiel has yet to heal. After reuniting with Daryl, she calls him her "best friend" and suggests that the two run off together. They fantasize about what the rest of the world is like, and discuss plans to leave for New Mexico. Carol wants to leave right away, but Daryl tries to convince her to stay, at lest for the time being. Depending on where The Walking Dead decides to take this storyline, it could end up with both characters leaving the show for good.
If this is what The Walking Dead is building up to, it's unlikely to occur until the end of the Whisperer War. Looks exchanged between Carol and Alpha (Samantha Morton) are a clear indication that Carol's disdain for her son's murderer will heavily factor into the story for both characters in season 10. A "smackdown" between Carol and Alpha has already been teased by Walking Dead producer Greg Nicotero. It's possible that Carol and Daryl may follow up on their conversation in the premiere once Alpha and the Whisperers have been dealt with.
The departure of Norman Reedus and Melissa McBride would be a major blow to the The Walking Dead cast. The AMC series is always killing off key characters, but in recent seasons, the show has lost a sizable chunk of its longest-running people. Carl (Chandler Riggs) was killed off in season 8, and the show's star, Rick (Andrew Lincoln), left the series early in season 9. Michonne (Danai Gurira), who has been on the show since season 3, is expected to leave some time this season. If and when Carol and Daryl exit, The Walking Dead will have no one left from season 1, and the only character left over from the first three seasons would be Maggie (Lauren Cohan), who is coming back for season 11.