They haven't decided if they want to do another Cloverfield movie. At the moment, no one can agree on "how" to do it. Some of the rumors I've heard was:
1) The sequel will take place on the same night during the same attack, only with a different group of people documenting it.
2) Prequel where we see the events leading up to the attack on NYC.
I like both ideas. I really hope they eventually do something.