We are, of course, all presuming that there will be a psionics "System" as opposed to what we have in the Monster Manual already, listing as "Psionic Magic" and giving the "psionic" monsters already existing psychic-flavored spells. It is simple and, in its simplicity, elegant. But will not be enough for the "psionic/psychics" fans who want their Jean Greys and Prof. X's, other [phsyical based/psyschometabolic] "X-men"/Superhero types, and Jedi [the last I would submit is already easily doable with an Eldritch Knight, though no idea if that was an intention of the design].
For example, those calling/hoping for a feat for those random [1e style] psychic powers anyone can take...when the Magic Initiate already exists and can give you a random "Psionic Talent" now, as is. Just flavor your spell choices and "casting" accordingly. Do we really need a separate "Psychic Talent/Mental Power" feat? Do we need a different/separate mechanic to make that character? In all objectivity...no. We really don't. Those of us who love the psychic archetypes WANT one...presumably to add to the flavor distinction that psionics is not "just another magic." But we don't really NEED one. As someone said upthread, and is correct, the distinction from "magic/powers" from Arcane to Psionic is really no more necessary of distinction than Arcane to Divine...and so, obviously also, Divine to Psionic.
The distinction of "inner/mental/self power" versus something that comes from an external power source, which I grant is a huge difference for the "meta-game" conception of psychic powers...but is, really, just a matter of flavor/fluff, a story/narrative distinction [though I hesitate to use that word for fear of those jumping on the RPG "narrative v. gamist v. whatever that is play" nonsense].
Do we need a separate system that somehow conveys "inner/personal power"? Again, not really. We already have one. They, rather short-sightedly, called it "Sorcery Points." [and my 2 cents for that would be that it was so-called for some added distinction for the sorcerer from the wizard] But it's there already. Bardic Inspiration could, likewise, be used as the mechanic for their powers...somehow. Or ANY existing mechanic with things restoring after short and/or long rests.
I want psionics. I love my X-Men/psychic character concepts. I would like -as I've said- a separate class with discipline based subclasses, and a feat for anyone...But I don't really want or need another separate mechanical system/layer of complexity to add...with little more than different names justifying mechanics we already have.
What was my point here?...I feel like I got all tangential...Who's using their psychic powers on me?