Sci-Fi website IO9 talked to JJ Abrams at Comic-con, and according to them:
There will be a Cloverfield 2 ... but it won't be a sequel. It will be something "surprising," said Abrams. [Here is] what Abrams told us on video about what the most important monster feature is, from the perspective of a guy who has created a lot of monsters.
Maybe that explains this sign in Pasadena (or maybe it is just BS)...
* Thanks to FringeTelevision for the story, and to Kristen S. for the photo!