I think we're pretty safe here. The Cloverfield monster design had no historical precedent for it's biological structure and characteristics. He was trying to come up with something as different as possible from the giant monsters we've seen before, which basically amount to a few lizards, a gorilla, and Glenn Langan. Thus, he tried too hard and overdid it a bit with the monster. Piranha will very likely be different. We have historical precedent for its biological design and we also have different creative minds in charge of this movie. The creature designers don't get absolute autonomy from directors and producers. We'll just have to trust "those" guys not to green light anything too ridiculous.