I kinda like the idea, I could see it totally working as a neat PrC.
Much more imagination could be put into it, unlike the crappy Dragon Disciple.
You could get a Breath weapon then have it's damage and type increase and change as you gain levels.
It' wouldn't be very hard to make it a point based system too so every one with the class could be a little different, unlike the crappy cookie cutter Dragon Disciple.
Someone could grow dragonwings and fly really well, another might grow scales and hav great AC or DR, yet another might incease in size or grow claws, yet another person could have powerful firey cone dragon's breath, and another could breath diffrent kinds of dragon's breaths.
And then someone might have lots of those powers together but they just aren't as strong as they could be.
There are a lot of possiblities.
But, I do think this should be moved to House Rules.