Why are they neutral? The prime, True Dragons are all quite inherently un-neutral. Unless he's drawing on the Psionic Crystal Dragons, it should require him to be not neutral on any aspect of his alignment. The Metallic Dragons are either Chaotic Good or Lawful Good; the Chromatic are all Chaotic Evil or Lawful Evil. Not a speck of neutrality in the iconic bunch.

Likewise, your feat requirements are...stringent. Five feats is an amazing task; even classes like the Archmage require only four. Granted, Skill Focus is a bonus feat for the Dragon Shaman, but even still.

Additionally, dragons are covered under Knowledge: Arcana, not Nature, and requiring a 200,000 gp equivalent horde is...rather insane. That is the entire allotted Wealth-by-Level of a 15th level character as a prerequisite for a PrC that is supposed to be entered by 11th level...not really feasible. I get that this is essentially a handout, but if you're going to go to the trouble to create it, with prerequisites like this you'd be better off just listing a single qualifier:

Special: DM gives you this class.

I like the idea, I'm just not a fan of the execution.