But I wouldn't be surprised if Ethan returns with revenge on his agenda.
Considering the stuff Sidwell has done to so many of his family members, it would be more appropriate for him to ally with people out to take Sidwell down. Sidwell tried to kill Holly, Lucky, and Jason (among others) in Africa, and menaced Sasha a bit before moving on to Laura, Carly, and everyone else in PC.
When will Willow strike against Kai and Trina now that she knows that they know?
I'm no Trina fan but I don't think she deserves to have a third boyfriend die on her, so I would imagine they write him out by having Willow get him some out-of-town job offer. Not a bribe, but more of a "distraction" to make him less likely to consider ratting her out. As for Trina, she has the advantage of all the others who know: Alexis, Diane, Suzanne....if Willow thought of doing something "drastic" to Trina, Trina only needs to point out that she'd need to also do something to all the others.
A plot I'd love to see: bitter Pascal switches the labels on the medicines in Sidwell's safe. Willow starts giving Drew the meds that keep Britt's Huntington's at bay, which have no effect on him, while Britt seemingly has a Huntington's relapse on the paralytic medication, ending up bedridden and no longer any help with the cold-fusion project. Britt keeps blinking "You moron!" in Morse Code to Brad, who asks her if she needs to borrow Liz's eye mites medication.