They need a Psion class, and until they have one, I'm going to be pretty frowny-face about all their psionics stuff. What's particularly ridiculous is, they HAD a perfectly good one with the Mystic, it just needed tweaking, but they threw it in the trash due to what appears to be internal WotC infighting. The excuses they give here are trash, frankly. The Artificer is a bigger problem in terms of "encroaching" yet apparently that's not a concern? Come off it.
That said, this is a considerable improvement on what they had, if largely because they're clearer on what they think Psionics is (not exactly the same as what I think it is, Psionics doesn't "cast spells" guys, but any clarity is helpful).
Ditching the Psionics Wizard is great, even if I say RIP to Id Insinuation, a spell I'd been using to great effect on my Bard in an Eberron campaign (there's always Dissonant Whispers).
The die size changing thing is completely silly. How could anyone even write that down? You get lucky twice in a row, even when you don't want to be lucky, and basically all your subclass abilities become unusable? What on earth?
If it shrunk to a minimum of d4, and could come back up, that'd be fine, if unnecessary and fiddly. You have can reset it 1/long rest, which is awful, because you could literally get a total of 4 rolls out of it (until it upgrades, then it's 6, then 8, and so on), and they might not even be necessary (i.e. you roll a six on the long jump when you didn't need to jump that far, just longer than before). They should either remove the mechanic entirely, bottom out at d4 (keeping the reset mechanic), or let you roll a smaller die intentionally, and have that not count towards either increase or exhaustion.
Some of the roll-based abilities are pretty awful because you as a player have to assume you're going to get 1, and you can't count on anything else, and there's not even necessarily any benefit on getting a higher number (Psionic Discovery being a prime example - you're not going to do that unless you need the spell in the next hour, and having it for longer probably isn't going to help you).
On a personal note, it seems really weird Mind Sliver gets removed from the Bard spell list, but stays on all other Arcane casters. It's more appropriate on a Bard than a Wizard, by miles.
Feats seem solid. Telepathic Feat would solve a lot of problems and be cool for a lot of characters.
But if WotC really aren't going to give us a Psion-type class, that's clearly internal politics, not "the players have spoken", and it's completely ridiculous. If they do Athas without doing that, it's vandalism.