I know its a moot point for Chris because his players have been limited to PHB 1 classes and races, but I am rather curious as to how to deal with seeds for Primal and Psionic classes, as well as all the races he excluded. In theory there is nothing in his design that procludes the use of any race or class that has been published, but I'd be interested in how he'd add hooks for the ones that had previously been excluded.
For Primal classes, the thought occured to me that there could be a few major or minor cults that had various plots in reshaping the world to the pre-cataclysm form with much more land. Maybe the massive oceans have weakened their conncection to the world spirits, and dampened the rages of those that walk the barbarian's path? One cult might have a desire to solve the mysteries and problems of the Demonmaw Sargasso. Another might try to steal the power from the Thunder Lords and gain dominion over the Frostfell. Another cult might be interested in raising most of the land that had been submerged by the deluge that made it into a Waterworld. Another cult might be trying to push back the Black Curtain forever, with a bunch of possible outcomes from that.
The struggle for me has been an all-encompassing hook for Pisionics as a whole. It probably has a lot to do with the limited amount we know about what will be Psionics, but we DO know that Monks and Psions are psionics, and other than the fact that their power comes from a deep introspective of one's self, they don't have much in common. Psions have a strong connection to the Far Realms, if its played out in Iomandra, but Monks don't have that hook, in my mind, without first tying them to the Githzerai race.
As for races, thats a bit more esoteric. Mostly, the world was built to rigidly follow the guidelines built for 4th edition, with the exception that dragonborn are the most prevasive of the world. This means that many of the offshoots of the Human race, i.e. Githyanki and Githzerai, goliaths (I view them as humans that have grown physically more in tuned with the earth, like Dwarves, but surface dwellers, so hence the larger frames), shifters and possibly minotaurs, might not make sense in Iomandra. I could very well be proven wrong, however. So, what would you guys do to make hooks for these options?