Take a look at the first official synopsis, provided by ComingSoon:
As humanity picks up the pieces, following the conclusion of Transformers: Dark of the Moon, Autobots and Decepticons have all but vanished from the face of the planet. However, a group of powerful, ingenious businessman and scientists attempt to learn from past Transformer incursions and push the boundaries of technology beyond what they can control — all while an ancient, powerful Transformer menace sets Earth in his crosshairs. The epic adventure and battle between good and evil, freedom and enslavement ensues.
Hmm, “an ancient, powerful Transformer menace sets Earth in his crosshairs”? Well, I don’t know about you, but that sounds a bit like Unicron to me. Michael Bay would certainly have a field day with that guy. Just imagine the amount of explosions he could do!
Could this mean we’re about to see the biggest, baddest and most destructive Transformer in the universe? Let me know!