The trailer's final scene is of season three's big monster (or one of them, at least). It appears to be growing larger and larger in the hallway of what looks like a hospital, with Nancy and Jonathan on either side of it, looking on in horror. This is important for a few reasons!
First, it's a pretty dangerous-looking monster, you know? That's never fun. Second, judging from the way it expands in the trailer, it seems like the monster is growing from a human body into . . . that. Perhaps this is the end result of whatever infection sweeps through Hawkins? That monster could be Billy! Or Steve, depending on what he's been injected with!
Also worth noting is that the shot of Bruce the journalist seems to be in the same location — see the tiles on the hospital ceiling? — so the monster could also be him. Or he's going to be a truly awful character who tries to ruin the lives of our faves, so we'll all cheer when he gets taken out by that monster.
In short: JULY 4 CAN'T COME SOON ENOUGH!
