Perhaps Jim is being held at gunpoint in the trailer because Jeremiah blames Jim for Jerome’s death and directed Ecco to take him.
Sure, Jeremiah and Jerome weren’t exactly bosom buddies by the end, but they were brothers, and Jeremiah’s mind might have been warped just enough to believe that Jerome’s death needs to be avenged, and Jim is the only one (other than Jerome himself) who could be blamed for Jerome’s death.
Of course, he could also be driven more by revenge than an overall desire to create chaos.
If Jeremiah is as far off his rocker as Jerome was off his, we can bet that he’ll use his considerable capacities as an intellectual to find some incredibly dastardly way to do damage to the innocent people of Gotham.