Hey, I just realized something while reading wikipedia
http://transformers.wikia.com/wiki/Unicron
Before the dawn of time, Order and Chaos existed within an extradimensional entity known as the One. He created twin astral beings to reign over the cosmos: Primus and Unicron. Their nature differed, as Primus' lifeforce (aka the Allspark) was a multiversal singularity; existing across all Transformers realities at once (see note below), whereas Unicron existed in only one dimension at a time but could travel relatively freely between them. Primus was the Lord of Light and Order, and Unicron, the Lord of Darkness and Chaos. Unicron sought to devour everything that exists and become one with The Void at the end of all things.
So if Primus' life force was the Allspark, which we already saw in the movie. Then there's a very good chance that Transformers 2 will feature Unicron?