I think the reason for putting Psionics first, out of alphabetical order, is because it's shiny. Psionics is the new thing in PHB3, so putting it first makes sense.
Baseless speculation tells me that we will probably see the Archivist and Templar classes for Divine (a different sort of controller and defender respectively), and the Totemist and Witch for Primal.
Baseless speculation tells me that we will probably see the Archivist and Templar classes for Divine (a different sort of controller and defender respectively), and the Totemist and Witch for Primal.