See, I don't even think of it as "faking" the psion, though. To me, the definition of a psion is someone who does supernatural things by drawing on the inner pool of power some accident of birth endowed them with. That view and usage predates the existence of the Sorcerer class.
The 3E Sorcerer was added just to give people a way to play an arcane caster without having to deal with the worst aspects of the psuedo-Vancian system. It had absolutely zero thematic powers. Those were added in to justify its continued existence in the later editions that were more mechanically clean for Wizards. The thematic aspect of Sorcerers addresses a problem that wasn't actually a problem. The Psion is the class that gets magic (by any other name) because of their nature.
I'm fine with adding a "Mystic" class that mainly just gives more visibility to the Monk's ki (like 4E did by putting Psion and Monk under the same power source). I'd expressly like to avoid the stupid ectoplasm, chimes, symbiote skins, and ambulatory crystals of 3E, though.
I'm not horribly opposed to the idea of creating a new Psion class, from scratch (as long as the ectoplasm doesn't come with it), and baking variety into the spell list(s), etc. But, really, it'll just end up being "the Sorcerer done better". You don't need both classes, thematically. Both are supposed to represent characters that have innate magic. These characters shouldn't all have the same spell list. Things like the Divine Soul and some others that have come out of UA with modified lists should be the norm.
