Hello!
Since we only have vanilla-type of the draconic bloodlines there is no option for neutral lined alignments to pick from.
I would like to ask for addition of more bloodline types, both from true dragon we have in sources.
What we currently have:
If the dev team decides to add more types of dragons and their bloodlines, even if initially just using the vanilla available textures and just matching the breath element we will have these options:
Legend: Name/Type [suggested/temporary colour] (element)
With this roster we end with 23 types of dragons and their bloodlines, each with their own personality and element variation that will not limit players to choose which element they like and type that would fit their character and alignment. In the end a lot of RP opportunities 
For the elements themself they are just suggestions, i doubt the team would let players breathe psionic type of damage, or knockdown breath 
Im open for feedback