I was thinking now would be the perfect time to bring in Unicron as the new threat. Once he realizes Cybertron is now a wasteland and the matrix is gone, he sends Scourge and Cyclonus track down it's location. Once they discover it's on Earth, have them retrieve Megatron's body so Unicron can resurrect him as Galvatron to assist in getting the Matrix. BAM! We have new villains, we have a new evil plot, and a new group of bad guys. What do you think? Yes? No? EDIT: Doh, didn't mean to type "storyline" in the title twice.