The packaging for a Revenge of the Fallen Missile Mania game features a redesigned Megatron on its front cover, despite supposedly not being in the movie:
For more clues on Megatron’s return we need only turn to the back of the toy boxes:
Starscream:
The moment his sensor net registered Megatron going offline, Starscream knew that battle was over and the Allspark lost. He converted to vehicle mode and boosted for outer space, hoping to buy enough time to rally the Decepticon survivors. Returning from Cybertron bearing the marks won during his reign over the Decepticon army, he is cocused on conquest. With a new army behind him, he has the strength to pursue his own goals, and perhaps, when the time is right, bring Megatron back.
Not to mention the Megatron Tank mode…