Rick Flagg is on the team, he Deadsho soldier and hero. Same can be said for Kattana, though she is a warrior out for vengeance, both her and Flag have the moral compass of a hero. Two will die, with the possibility of a third's apparent death if she is the true threat as rumored. First the safe characters. Joker, Harley, and Croc they won't be killing major Bat Villains. Deadshot is a long time core member of the squad and has uses elsewhere in the DCEU. Same for Boomerang plus Flash hasn't even gotten started yet, can't start taking away his toys. Depending on DCs plans beyond the JLA & 2020, Kattana is probably safe as well, given her role in Outsiders, Birds of Prey, & Green Arrow. That leaves four. Slipknot is going first, he will be used to show the others that Waller is not messing around if they step out of line. El Diablo is cannon fodder. It's possible Rick Flagg will play the role you described for Deadshot, he doesn't have much history with this version of the Squad and doesn't really fit anywhere in the DCEU. Finally there is Enchantress, there's no way the kill her. She is too big a part of the mystical DCEU. They can make it appears she dies or that June is cured. Either way the fact she never appears with the Squad makes me think she is the mission. That's very bad news for the Squad. She once took out Superman, Wonder Woman, and Cyborg with a thought.