Matt Reeves wrote ...
There are also two things at the end of the movie. There is the voice that you are referring to, but in the final shot…there’s a little something. The stuff at Coney Island, there’s a little something there. There’s something dropping in the water.”

wrote ...
With an ending like Cloverfield had, and all the loose ends, the possibility of a sequel is probably one of the hottest questions out there. When Reeves was asked if he could see himself directing a sequel, he energetically replied:

“Sure, if i think the movie that sort of came out of [Cloverfield] was compelling for all of us. This idea was so compelling to do and we had so much fun in doing it because we had never done anything like it. So i think we would want to find a similar challenge to this, to find it having its roots in this but be fresh and new because otherwise you are just repeating yourself.”

That’s fine and dandy but when push comes to shove, I just don’t know where you could begin or even start to formulate a sequel that is similar to the experience of Cloverfield. So when asked what a sequel could look like Reeves told us that:

“There was a guy who was off the side of the bridge and Hud sees him filming, so he turns and sees the ship that has been capsized and sees the headless Statue of Liberty and then turns back…and [the other guy] is briefly filming him. And so in my mind that was two movies intersecting for a brief moment. And I thought that there was something really interesting in the idea that this incident happens and there are so many different points of view, and in a way there are several other movies at least that are going on that evening and we just saw one piece of another. We would have to see if anyone would even want a sequel and see how the movie does. If the movie does well and there is a compelling reason to do so, I think it would be fun to do a sequel.”