I'm getting the same parallels from the myth. 
The murals seem to depict dragons in flight, as allies of the Arlathani. (I'll make that a word, by gum.) They could be dragons coerced, Temple of Mythal style, or they could be the gods themselves and their followers in the 'form of the divine'.
My latest theory drabble inspired by your post that Elgar'nan and Mythal led a rebellion of sorts against the dragons everywhere, and used their blood and knowledge to establish themselves as the new gods. They tossed down the Old Gods with the aid of the dwarves, sealing them away. They used shapeshifting (which you have to know the soul of a creature to use, according to Morrigan and Shale's banter in Origins) to assume the form of the Old Gods, because hey, dragons literally rule.
I'm unsure how red lyrium and the Blight figures in here.
The dwarves may have gotten paid in just plain gold, they may have gotten trading rights, military aid against a dwarven rival, the Titans may still have been in power and made an alliance with the Arlathani. (The Titans, it seems, were the creators of runes, which I imagine where used on a never beforeseen scale to seal away the Old Gods.)
Kieran having lyrium nightmares implies a ton, but I can't make anything from it.
Not yet, at least.