So, just what is your answer to address the problems that will arise between spellcasting dragons vs. melee dragons, and hybrid dragon builds vs traditional dragon builds vs non-traditional dragon builds with changes to their single school? Just how do you intend to make the single class with a variety of builds in it that equate to monk, warrior, battlemage, etc. more interesting or balanced between all of them by changing any of the present abilities without leaving someone or something out.
Remember, it has been made
very clear that dragons will not get multiclassing, so that is not an option. Any answer can not contain multiclassing.