The Pathfinder SRD lists 34 bloodlines for sorcerers, with another 10 from 3rd parties. That seems to me to imply far more potential flexibility in player concept and DM campaign design than seen in most classes.
Umbran, it looks as if you were responding while I was editing my post for clarification. One issue that I have with the Draconic Heritage presented is the same issue that I have with Pathfinder. Unlike, 3e heritage feats, they are not as flexible by default. The heritage feats allowed a player of a given heritage to take some, all, or none of the heritage abilities as they leveled. Players could choose something a different feat or, with the exception of the initial feat, take a feat after the minimum level at which it the feat was available. This gives more flexibility in individual character growth and than the hard prescribed powers at a specific levels of the Dragon Heritage or Pathfinder bloodilnes (which, to myself, often seemed to be too arbitrary and would have been better with more options for individual heritages).
A cite on that assertion would be good, 'cause I haven't seen such a statement.
As for casting and unique classes, it is not set in stone, but the following is from Rule of Three 6/26:
In D&D Next, will a different spellcasting system likely be attached the wizard, or to a different class?
For the moment, we're looking at big structural changes (like, for instance, how a character casts spells) likely requires a different character class. While we are definitely excited about the idea of having different ways of casting spells, we also want to make sure that our classes stay balanced and functioning as intended. Plus, it makes it a bit tougher to predict how other game elements (like feats, for example) interact with a class when that class's fundamental mechanics change. In the other direction, we think "alternate spellcasting method" is a strong enough hook to give a class a large portion of its mechanical identity, and again we can really make sure that the class is behaving in a unique, balanced way if we focus all of our efforts on that class's core mechanics.