Too many more classes and they are just going to get stupid. Some kind of are already. A few more would be nice but too many more will be too much.
I agree that there there is a wide selection of classes now, at the absolute least I'd like them to round us out with another mage and healer. I very much enjoy new classes, as long as they're different than what has come before, and not too overly powerful. That being said, I don't mind that Heirs of the Blood doesn't have them. Speaking of the "when," the FFG list states that it's expected Q1. I'd guess February- waiting for "Guardians of Deephall" to emerge, presently.