Although that being said... these two new ones that we've just seen-- the Aberrant Mind and the Lurker in the Deep-- are definitely not Dark Sun themed (there sure ain't no Deep in Dark Sun for anything to Lurk in!). So maybe the idea that they were going to use Dark Sun as the foundational book for psionics has been changed as well? Maybe they are going to have a Xanathar's Guide type of book (focused maybe on planar or underwater stuff?) instead and have psionics appear in that.
