Thea being dead would be such a pile of horse shit to kill off the only thing that should happen with Thea is her being the one to kill Malcolm and having zero regrets and not even an ounce of sadness in doing it while telling Oliver to fuck off with his bullshit as she leaves Star City.
Chesthair is the only one of the main cast that's expendable at this point, I just hope Malcolm dies too. I do kind of want Thea and maybe even Laurel to leave Star City for a while. I was thinking about this last night and I'd have Laurel being taken by someone while Caitlin on the Flash also disappears, I probably should've wrote some notes down but I was about to go to sleep. Thea's not being on TV every week can be explained with her following leads outside Star City, maybe have her show up in a Flash episode or something.
Basically the first part of the next seasons of both shows would be involve trying to find them without a realization that their disappearances are connected for at least a few episodes, Caitlin's disappearance would happen in the off season with her quitting STAR Labs in the finale so they wouldn't even think about looking for her and assume after all the shit that's gone down she went off the grid. While Laurel would be abducted in the S4 finale by Adeline Kane/Wilson (Slade's ex-wife). I had some ideas for cross overs and such thrown in but it'd turn out to be H.I.V.E. Which shouldn't (and better not be) be entirely wiped out this year, Caitlin eventually just turns up in the Fall finale with a reveal (while the other characters aren't around of course) that she now has Killer Frost's powers in the stinger. Arrow's Fall finale reveal is showing Laurel still prisoner at the facility (if they could get Slade back, even better) where they've given her the actual, not the high pitched emitter thing that doesn't work half the time, Canary Cry. Later it could be revealed that Laurel broke people out before being recaptured or could just be Caitlin was let out with a job to do since she's now a heat vampire and H.I.V.E. Are the only ones who have what she needs without killing.
This was better in my head when I was thinking about it last night and I could probably work on it to make it so but it's late. I'll be surprised if they don't just destroy H.I.V.E. By the end of the season but I still want Slade's ex-wife to be the real person in charge, especially with this Damien Darhk business seems to be winding down after that last episode and there has to be people above him.