Yeah, Trish as a villain would never work. Trish and Jessica care for each other too much that they won't kill or hurt each other in a really bad way. And having Trish as a villain would mirror Season 2 too much, with a lot of the conflict stemming from family. I think that whatever the threat is in season 3, it would make more sense to have Jessica and Trish both going after it and thwarting each other as they butt heads, with the impetus being a mix of Jessica still not being able to look at Trish because of her choices as well as her judging Trish's techniques as a newbie hero without yet understanding the responsibility that comes with her abilities and how it could lead her to become no better than the bad guys. This could come to a head where Trish finally gets it and tries to get Jessica to take her on as a peer/sidekick to teach her, which will be a long road of refusals that ultimately ends in concession and Jessica forgiving Trish, due to the nature of the threat they are up against. With Malcolm, he'll likely come back to work for Jessica once he begins to take issue with the sorts of things that Cheng tasks him with doing, and will come to realize he misses working with Jessica and thus go back to her.