The potential return of Maggie (Lauren Cohan) in season 10 of The Walking Dead could introduce a new community to the AMC series. Cohan exited the series in the first half of season 9 to star in ABC's Whiskey Cavalier, but the door was left open for her character to return in the future.
In the first five episodes of season 9, Maggie's story revolved around her issues with Rick and his handling of Negan and the Saviors. There were concerns that the conflict between Rick and Maggie would erupt into a civil war. In Maggie's final episode, she went to Alexandra to take revenge on Negan for the murder of Glenn. After seeing that Negan was already a broken man, she determined that killing him was no longer necessary. After the six-year time jump, it was revealed that Maggie and her child left the Hilltop to help build a "new community" with Georgie.
Maggie's connection with Georgie could provide the perfect entry point for The Walking Dead's next community. Introduced during season 8, Georgie was a mysterious survivor from an unknown community who made Maggie an offer that was too good to pass up. In exchange for old vinyl records, Georgie gave Maggie books that would them rebuild civilizations. It was Georgie's books that served as the foundation for the developments that were made during the break between seasons 8 and 9.
The Walking Dead showrunner Angela Kang hopes to be able to continue Maggie's story in season 10, but it will all depend on Cohan's schedule. If Maggie does indeed come back in season 10, the best way for that to occur is to have her act as a bridge between the show's current communities and Georgie's community, who is clearly more advanced than the others. If and when Maggie comes back in season 10, she could introduce the Hilltop, the Kingdom, and Alexandria to Georgie's people, and perhaps explain exactly what she was doing in her long absence.
A popular fan theory is that Georgie represents the Commonwealth, an organization which debuted in a recent story arc of The Walking Dead comic books. The Commonwealth is a large network of communities that consists of 50,000 survivors.
Since the characters currently have their hands full with the Whisperers, it's unlikely that the Commonwealth will appear again anytime soon. However, the Whisperer War could wrap up at some point in season 10, allowing the show to segue into its next major arc, which could be set into motion with Maggie's return.