Some reasons a sequel makes sense:
[SPOILERS BELOW - DON'T READ IF YOU DON'T WANT TO SEE THEM]
--One of the key features of the movie is that no explanations were given. People are naturally curious, AND WON'T STOP SPECULATING, about the origin of the monster, the fate of the monster, the small monsters, etc. That's as tailor made for a sequel draw as you can get.
--There are plenty of characters that could continue the sequel, IF they want to build on any of the character's experiences. Such as:
Lily flies away in a heli, presumably safe.
Jamie is passed on out the couch at the party, presumably survives.
Jason is there, then he isn't, when the bridge is attacked, but we don't actually see his body or death. He could have been knocked into the river.
We don't actually see any proof of Rob and Beth's death. Obviously the military found the camcorder, with the tape intact. Perhaps Rob and/or Beth are sedated in a military hospital after the discovery.
--The producer/director stated in interviews that the genesis of the idea was upon seeing shelves of godzilla merchandise in Japan, and realized what a franchise it was. This is a business, and the word franchise has a certain appeal. There's money in a sequel, and even more in establishing the cloverfield monster as "america's godzilla". Money for years.
--There's absolutely no reason the first person POV would deter a sequel, and I would think they would avoid that same technique in a sequel. We all get the sense that the video is being viewed in a military office or bunker by the DoD text at the beginning. Well how natural to pick up the sequel in that room as they turn off the video, and start talking about how the monster took all they had and is still kicking butt. Or that it disappeared into the ocean minutes before the hammer came down on NY. Lots of easy paths to start a sequel from.
Nick
www.KidReviewer.com