I think that one of the designers have said that psionics wold be in the PHB2, or my brain is melting and can´t distinguish between fact and rumour.
But, besides that, i would say that i prefer that OA is put out as a diferent product, because eastern fantasy is its own genre, that must be somehow described and worked into the book, one thing that i don´t that belongs in the players handbook is that descripition of how the genre works. If they do make a DMG2 with this kind of stuf to complement i think it would work out great.
To think of it, this aprouch is one kind of thing that i would like if they do it, DMGs discussing diferent genres and thakes to fantasy, with notes of how to adapt the classes and how to work the game in that direction. For example, the DMG2 cold be the companion for the PHB2 that have oriental, psionic and steampunk classes, and discuss how to create a word and adventures around that genres, and the MM2 cold have moster tied with these new power sourcers. It would be a great way of introducing suport for diferent kinds of games and could replace the actual "Heroes of..." series.