Ms. Vaughn: "I should have seen it coming..."
Ms. Bannet: "I saw it coming. I told you it was coming. It's still coming..."

Our interpretation is, that Ms. Vaughn and Ms. Bannet knew about the relationship between Paulie and Tori and they saw that problems might come up soon. They knew also that the character of Paulie is a wild and beautiful one, but that she might not be able to deal with loosing Tori, if there ever anything would happen.

Later they knew about the big problems between Tori and Paulie and thinking back Ms. Vaughn says: "I should have seen it coming..."

And looking in the future, Ms. Bannet might think / fear of what all still might come when she says: "It's still coming..."