Takara's Alternity website has updated with a silhouette teasing the next car in the line. Megatron and Optimus Prime have already been released with Bumbleebee and Cliffjumper coming in the next month or so. This silhouette indicates a sports car whose shape reminds me of Generation 1 Sideswipe.
Speaking of Alternity Megatron, that toy is getting a third iteration with Diamond Black Megatron. It’s identical to the preview versions (blue and silver) only the primary colors are black and a dark red. Click here to view the gallery. Thanks to Ben1227 for the links.