Not really, as a game its all about numbers and the implementing to a game,
and because there are 3 psionic classes what are already regarded as base classes, ad because NWN2 implemented the 3.5 rules quite good (not perfect but good) they can simply be added, and similar to sacral and arcane powers it only becomes a3rd option. United with the ability to multiclassthem as all other base classes (Wizard/Psion, ect.)
I can't see anything that would be a trouble to include them at all, except for 'why if we don't have to?' or 'meh, we are too lazy for that'
but because the new base classes are already said to be included, i don't see many other possibilities to be it, if not the psionic classes.
After all these psionic/gith things it wouldn't be too far to guess that maybe the second expansion will have the 2 gith races including as playable too.
Im sure they hold their word, and maybe make other things ridable too (spider, dragon, lion, big rat, pony version of the horse, lizard, ect.)
*sigh*