Maybe Shockwave comes to earth with cybertron and cybertron acts as another moon to the earth, a dark moon. And the decepticon army comes from cybertron to invade earth....
Similar to what happened in the original g1 series, thats my guess anyway.
Starscream better try and destroy megatron in this one too!!! ALL HAIL STARSCREAM!
I think that jet thing thats been seen recently is how they get from cybertron to earth aswel maybe, who knows. I'm actually looking forward to this film tho, just hope its not a let down like the 2nd one and its not all about bumblebee.
Shockwaves looking great too, might be the first movie toy i buy