UNICRON!!!!
As quoted in Movietime Magazine, the writers of the Michael Bay Transformers movie, Roberto Orci and Alex Kurtzman, say in an interview:
We can't say much right now, but as we are almost finished writing the screenplay for the sequel, the action will be bigger than the first one - literally bigger - as in our heros and villains [Autobots and Decepticons] reluctantly teaming up to fight a certain evil planet-sized Transformer.
okay, this is getting annoyying, they never said they weren't writing the sequel, they just said they haven't signed on, no one has except the actors who signed for more than one movie!
and the writers of TF1 have already stated that they will not be writing a sequel.
IF they do unicron have james earl jones do the voice
Na I would keep thinking hey its Darth Vader. Have Nimoy be Unicron
voice not deep enough he don't like transformers
from what i heard