Actually, I have often thought that if the devs wanted to introduce alternate-classes for Dragons - it would be easiest to just put them in for after the 100 level mark (and would also assist with the idea that bipeds get ratings higher than that while dragons do not).
Basically kinda like what Amon lined up - only you could ONLY specialize into ANOTHER dragon class (i.e you'd go from Melee DPS to Caster, or Melee DPS to Healer schools) after you had passed you AROP (at 100). Then, as an Ancient, lore-wise, it would also make the most sense because well - now you are an Elder and thus you have the ability and knowledge now to be able to learn new fight/heal abilities...
Just an idea that would make it simpler than overhauling the entire 1-100 experience - just add an additional/expanded experience for post-100 dragons. (Or perhaps the overhaul is necessary to keep from being OP at higher ratings/post 100..or perhaps the power would be kept in check because taking on the new school means some of your previous abilities would be on shared timers with the new school-specific-abilities or totally locked out)
Anyway, just a suggestion to throw in...