Maggie hasn't gotten along with the Hilltop community's leader Gregory since the very first time they met, and things have only gotten more tense between them since Maggie relocated to Hilltop. The root of their issue is their radically different approach to handling the threat of the Saviors: Maggie wants to take action whereas Gregory would rather play it safe. She challenges him constantly and it seems like Gregory is going to get fed up with that sooner rather than later. The promo for Sunday's episode, "Something They Need," showed Gregor approaching Maggie with a knife hidding behind his back while he wondered via voiceover why she was still at Hilltop. So does Gregory kill Maggie on The Walking Dead?
Don't worry too much about Maggie; if the show follows the comics, then she'll be around for a long time. In fact, Gregory is actually the one who needs to watch his back. In the comics, Maggie ousted Gregory from his leadership position and took over as the leader of Hilltop before the big war against Negan. Gregory remained in the community, but he didn't forget his resentment of Maggie. He made an attempt on her life by poisoning her wine, though luckily Jesus happened by at the right moment and she was rescued. Gregory spent some time in jail before Maggie decided that the only way to keep Hilltop safe was to kill him, so he was executed by hanging.
The show definitely seems to be setting up a similar situation, even if it doesn't play out exactly the same way it did in the comics. Maggie is primed to take over Hilltop; the people there trust her, and she's been fostering that trust by training the residents to prepare them for fighting the Saviors. This puts her in direct opposition to Gregory most of the time, and those tensions are sure to boil over. When they do, it might result in a situation very similar to the comics.
A sneak peek for Season 7 Episode 15 showed Gregory trying to made amends and offering to work together, but based on everything he's done so far, it seems disingenuous. Gregory has proven himself more than willing to work with the Saviors, which goes against everything Maggie stands for. Like in the comics, Gregory might be pretending to make nice with Maggie so that he can get her alone and try to kill her.
But while he might make the attempt on the show, there's no way he'll be successful. Maggie's story is far from done. The next phase of her life is really just beginning.