I was thinking about it, I think that maybe the Mutos are Dr. Serizawa´s  new Bio-Organic Weapons. Maybe he is they "Father"

EDIT: I think he will die, if he is even in part responsible of the Mutos breakout, the Mutos would kill him (That would be more dreamartic). If he don´t help to create the mutos, then Godzilla will kill him, anyway, in both scenarios, he will have chance to scape, but he will stay and get killed by the monsters because some kind of blame scence.

Since this is a modern Serizawa id imagine he will play a pivotal role in solving the Godzilla crisis along with the other monsters. Based on the footage shown and photos of him in hazmat gear id say he discovers the foes Godzilla will face in the movie which are later experimented on and break loose. Since Legendary has plans for Godzilla after this reboot if it does well i'd imagine he will attempt to come up with a weapon capable of matching Godzilla but in the end doesnt work.

This is a reboot, not a remake so while I can see bringing the character back for nostalgia I really disagree with the decision. 

It seems like scientist role has been given to Bryan Cranston's character so I have no idea what Serizawa will do. Perhaps the 2 will work together to come up with the missile you see being loaded in the preview or some type of anti Godzilla weapon.

It's been said before that there will be scenes in 1954. It's also been said that Dr. Serizawa will in fact make an appearance, but as a modern day iteration. The leaked script from 2012 that is still higly questionable basically had a scenario where it appeared to be an alternate Godzilla universe where the 1954 attack never happened. If we take all these into account (please take note that this is pure speculation based on tidbits of info not proven official):

Perhaps, if this is indeed a complete reboot and not another sequel to the original film, the characters from the original could possibly still exist canonically, including Dr. Serizawa, who's descendant, the modern Dr. Serizawa, would exist because the 1954 one never had to take his own life to stop the original Godzilla. The majority of them wouldn't know about the existance of Godzilla, and could be a pivotal plot point for those who do know. It's been stated before that this Godzilla could be considered the same as the original spiritually, but perhaps it runs deeper than that.

Again, all of this is pure speculation and should only be thought of as something lof interest, not taken as fact or official.

@KING_OF_ZOMBIES - That is actually a very good guess. I can't believe no one ever thought of that before! The MUTO's are more than likely Serizawa's creation. You're a genius hahaha :)