Possible Spoilers For Suicide Squad.
This is my first post on this website and I shouldn't take credit for this theory as I saw it on a trailer review by Jeremy Jahns, if you are interested in movie reviews check out his video and channel. Anyway he pointed out that it looked like Harley Quinn is dead so I thought I would continue on his theory. If you haven't seen the new Suicide Squad trailer I suggest you watch it.
All in all a great trailer, and obviously people would have started looking for hints and easter eggs and there are probably plenty. But the one scene that stuck out was when The Joker (Jared Leto) jumped into what looked like a vat of toxic acid then in the next shot he's holding Harley Quinn (Margot Robbie) in the same vat. Now when I first saw it I thought it would be part of her origin as seen in Suicide squad #7 Origin of Harley Quinn.
In this telling of her origin The Joker takes Harleen Quinzel to the same warehouse where he was 'born' for Harley Quinn's 'birthday' then pushing her into a vit
After Joker drains the vat he looks in to find a newly born Harley Quinn with blue and red hair.
In the trailer we do see something like this but with less context, we see Joker jumping into the acid and bringing Harley to the surface. When you see the shot of Harley in his arms you see blue and red dye around them which is the colours she dyes her hair in the trailers so the acid could have maid the colour leave the hair but for all we know that could just be part of their clothes melting.
If you look closely at Harley you can kinda see her Baseball shirt.
If that is her Baseball shirt that means that could mean she fell in the acid while being Harley Quinn. So could this be the big death in the movie? That's how the trailer makes it look with Joker diving after the one he loves.