I saw the trailer last night when it hit. Based on the tagline of the film, and the fact that
Spoilers: (Highlight to reveal)
The ending of Cloverfield made it clear that the monster survived "Operation Hammerfall" which is essentially a scorched earth type of maneuver that would carpet bomb the entire island of Manhattan
, and then after watching the trailer, my guess is that the movie goes like this:
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"Clover" survived and is continuing to wreak havoc, and the parasitic creatures it was dropping off itself in the first film probably run rampant.
John Goodman's character is likely keeping the two younger characters captive "for their own protection" (hence "Monsters come in many forms").
The movie will probably feature next to no visible Monster activity. It is not a found footage film. It is likely going to be a psychological horror-drama which focuses on the two younger characters' desire to get away from their "savior' John Goodman, whose sanity is rapidly declining.
I can almost guarantee you that the scene in the trailer where she runs to the entrance of the bunker and she seems horrified is the absolute end of the film, maybe even the final shot of it, and the only time we see any indication of the monster(s) other than the sound of the creature earlier in the trailer.