That leaves the I, T, and W as the new and unknown classes. There was a cryptic comment about witches, warlocks, and wizards before, so my guess for W is a Witch class. Despite the gender connotations, as Wikipedia says, "...in legends and popular culture the stereotype is female; however males were also often referred to as witches." Witch seems like a primal class to me, possibly a controller.
That leaves I and T, and no divine classes yet. But it says "divine" right there on the cover, so likely those two would be the divine classes, brand new. I've tried to come up with names that fit, and best I can manage is Inquisitor and Theurge. Inquisitor sounds like a Striker class, focusing on finding an slaying enemies of the god. Theurge sounds more controllerish to me.
So my list:
Bard (Arcane leader)
Barbarian (Primal Defender)
Druid (Primal Hybrid)
Inquisitor (Divine Striker)
Shaman (Primal Leader)
Sorcerer (Arcane Controller)
Theurge (Divine Controller)
Witch (Primal Controller)
Seems a bit controller-heavy, but then again the PHBI was controller-light and striker-heavy. Not sure what the Druid will be a hybrid of, but it could help balance things out.