Okay, I was looking forward to this archetype, but unless I'm reading it totally wrong, it seems to be a waste of feats except for a kobold and isn't this supposed to be more widely used?
First, only a draconic sorcerer, or a dragon instinct barbarian, or a dragon/spell scaled kobold can become one. The flavor text indicates that other characters can choose it, but the access conditions say that they cannot.
Second, since the sorcerer and barbarian can already get or wouldn't want almost all of the feats offered by the archetype, what is the advantage gained?
** Claws of the Dragon (4) only increases the die from d4 to d6 for the sorcerer, who normally isn't up in melee combat anyway. I know there are a very few melee sorcerers out there, though. It does seem to be an always-on ability, but the extra resistance would still only activate when using bloodline spells . A barbarian isn't going to switch their possible weapon damage down to a d6 (at least I hope not). Kobold is the only one who would use this.
** Draconic Scent (4) for barbarian can already be chosen as a feat and built upon if wanted. Sorcerer has much better things to choose from. Again, maybe a kobold would want this, depending on their own class feat availability.
** Dragon Arcana (4) for sorcerers is a no. A barbarian would have to take a previous spell casting archetype to use this. Again, only the kobold might want it.
** Scales of the Dragon (4) for sorcerers is a maybe since the item bonus from armor runes on explorer's clothing would stack with the status bonus, but that dex cap of +2 really hurts, unless you build specifically for this. Eh. Barbarian can do better with medium armor and a +1 dex mod and raise that with armor runes. For kobolds, it would depend on their class and, like the sorcerers, would want to build for this feat.
** Breath (8), Wings (12), and Shape of the Dragon (14) for a sorcerer are useless as they already have them. Barbarians, maybe, if they want the transform and the aoe/ranged breath is good. I'll admit wings and becoming a dragon are always great. Again, kobolds would love this part.
Third, I could have missed something, but it just seems that restricting this archetype to these three specific builds isn't what was expected, and even they would have to give up potentially much better feats to gain only a couple of usable ones.