Thank the gods for that. Trying to cram every psionic trope into one and the same class is stupid and clumsy design.
It would be so much cooler if they designed psionics to be an bolt-on mechanic to replace spellcasting for selected characters, laying a foundation to allow Psion to be a Wizard subclass, Psionic Warrior to be a Fighter subclass and so on.
That is: create a rule for power points (or manifestations, or whatever) but don't base it in one single class. Then have the subclass dole out the PP.
In fact, just say "psionic characters use the spell point variant of the DMG, only we're calling them power points" and let the existing spell slots be as-is. That's the direct and simple answer to the question "so I'm a psionic wizard, what am I gonna do with my spell slots?" That is, the answer is: "you only think you get spell slots, but in reality you get spell points that we call power points."
Boom, done, no rambling rules explanations necessary.
In cases where a character gets spell slots from the subclass and not the class psionic subclasses of that class can get PPs directly.
Then we can finally stop worrying MMearls will muck up this core design too, and start worrying about the details. I'm convinced they plan to give the Psionic Warrior lots of cool powers, only to ruin them right away with Concentration, for instance.