>>931339
They already did it in Transformers Prime Season 1, Episode 24/25/26.
If I recall correctly, he never gets the chance to fully transform, and can create multiple, smaller simulacra of himself made out of earthen metals, and he can possess Cybertronians, as he does to Megatron.
I suspect the movie will be similar, and the Autobots and Marky Mark will go deep into the Earths/Unicrons core to shut him down, just in the nick of time to prevent Unicron from transforming and killing all life on earth.