Taken from the Cloverfield/wiki page
Sequel
At the premiere of the film, Matt Reeves talked about possibilities on how a sequel will turn out if the film succeeds.[65] According to Reeves, "While we were on set making the film we talked about the possibilities and directions of how a sequel can go. The fun of this movie was that it might not have been the only movie being made that night, there might be another movie! In today's day and age of people filming their lives on their camera phones and Handycams, uploading it to YouTube... That was kind of exciting thinking about that."[66]
In another interview, Reeves states:
There's a moment on the Brooklyn Bridge, and there was a guy filming something on the side of the bridge, and Hud sees him filming and he turns over and he sees the ship that's been capsized and sees the headless Statue of Liberty, and then he turns back and this guy's briefly filming him. In my mind that was two movies intersecting for a brief moment, and I thought there was something interesting in the idea that this incident happened and there are so many different points of view, and there are several different movies at least happening that evening and we just saw one piece of another.[22]
Reeves also points out that the end scene on Coney Island shows something falling into the ocean in the background (pointed out by fans to be in the far right from the view out of the ferris wheel, a bit left of a boat sitting in the water seen falling just as the camera beeps), but didn't give out details.[22] (This is, however, many days before the start of the film and shows the two main characters on Coney island before they meet again at the start of the party — as shown by the date stamp on the footage from the camera. This relates to how events began to happen and the satellite which falls from orbit owned by the Japanese media company mentioned).
Producers Bryan Burk and J. J. Abrams also announced their thoughts to Entertainment Weekly about possible sequels. According to Bryan Burk, "The creative team has fleshed out an entire backstory which, if we're lucky, we might get to explore in future films".[67]
Abrams stated that he does not want to rush into the development of the sequel because of the first film's success and would rather create a sequel that is true to the previous film.[67]
At the end of January 2008, Matt Reeves entered early talks with Paramount Pictures to direct a sequel to Cloverfield, which would likely be filmed before Reeves's other project, The Invisible Woman.[68] Reeves now said:
The idea of doing something so differently is exhilarating. We hope that it created a movie experience that is different. The thing about doing a sequel is that I think we all really feel protective of that experience. The key here will be if we can find something that is compelling enough and that is different enough for us to do, then it will probably be worth doing. Obviously it also depends on how Cloverfield does worldwide and all of those things too, but really, for us creatively, we just want to find something that would be another challenge.[69]
In an interview with Attack of the Show, J. J. Abrams had stated that they might abandon the filming style, stating that he and the rest of the crew would like to try something new.[70]
In September 2008, When asked by CraveOnline what the current status is on Cloverfield 2[71], Abrams stated that at this point, they are still discussing it; however, he still feels reluctant to work on a sequel. In the same interview, Abrams said that they were working on something that "could be kind of cool." When asked if it would take place in a different location, Abrams replied by saying that "It would be a totally different kind of thing but it's too early to talk about."
In January 2010, J.J Abrams confirmed that a sequel is 'in development'.[72]