As it is done now, they can only specialize in one school really. They don't access any powers in the second school. This pretty much leaves palemasters as the only place they can spend extra points once they finish their one school specialization. When I was playing with the enhancements on my elven wizard, I thought up an additional idea.
You know how elves can get Arcane Archer unlocked if they work up their racial tree? What if archmages could work all way up to purchase their secondary school and unlock another archmage PrE? You could make it a replicate copy or slightly different like a minitariazed version of Archmage but the key idea is you'd get to select the secondary school powers. It'd increase diversity of the wizards and not everyone be forced into Archmage PM classes. (To give an idea, I had an illus/evo wizzy before EP, now she just evo with some necro stuff.. not really inline to her character)
Just a thought, open to suggestions~