The show revolves around the (teen) moms, who are the so-called talent or “stars” of the show. Each of the five moms - Jenelle, Kail, Leah, Chelsea, and Brianna, are listed and pictured in the show’s intro, and all the supporting characters like Nathan and Barb, Cole, Randy, etc., even the kids, are introduced in terms of how they’re related to one of the mom’s, ie. “Jenelle’s mother.” So if Jenelle is no longer on the show, then neither is her mother, regardless of how much film they might have of her in the can.
I understand thinking that they’ll want to include all this drama in one of the episodes, but dropping her storyline goes hand in hand with dropping her from the show. I saw a preview of next week’s season finale, and it showed Morgan Freeman (the producer) saying something about not filming Jenelle, so maybe they’ll include it in next week’s episode, although my guess is that that was in reference to all the pre-murder difficulties surrounding Jenelle as a cast member.