Ardent, Dreamer, Uncarnate and Wilder I can get behind - all of them have good hooks to build a subclass on. In fact Ardent is the one I want to see the most. I'm not so sure about the Specialist or the Electromancer. The Pyrokineticist I always go back and forth on - it's an archetype but it's so limited. Even if you allow them to control both heat and cold it still feels less thematic than I'd like. I'd almost want to roll all of the energies together into a single energy manipulator subclass of some kind rather than breaking them out as separate subclasses - fire, cold, lightning, thunder, maybe radiant and necrotic (throw in force and you'd have the general telekinetic I guess) - and then have the ability to choose more energies you can manipulate as you level up.
For a Cerebromancer, would that be a Psionicist subclass or a Wizard subclass? I like the idea, but the actual 3e implementation was basically "here's a patch prestige class to take for multiclassing psions and wizards because we know that caster multiclassing is broken" so I'd like to see the theme come out more and I feel like you could take it either as a Wizard who goes deep into the study of psionics or a Psionicist who has figured out how to tap into arcane magic with their psionic powers and then build from there.